I'm usually wary of deleting longstanding entries even if the term is uncommon. In this case the entry does seem off the mark. I think it can go.

checked 日本国語大辞典 koijien meikyo shinmeikai gg5 genius wisdom

I somewhat tentatively propose this entry for deletion. Rationale:

 * no other dictionary I checked seems to have this as an expression entry, or even to mention it in an example under 自信

 * very few google hits, and most of those seem to be where it's used as a survey/multiple choice answer option, like 「自分に自信があるか否か」を20〜50代の有職女性に調査したところ、実に62％が「自信なし」 which I think is just あり/なし being used in their usual way, rather than 自信なし being an expression with a particular meaning

 * 自信なし to me is more like "unconfident" than "unsure", so the definition as it stands is a bit misleading compared to if the user looked up 自信 and なし separately (unless this really does have a different nuance from base 自信, which I didn't find any evidence of)


Kyoto/Melbourne ngram stats, which I think somewhat back up the "this isn't actually an expression" theory:

自信	 306632	94.3%
自信なし	 1015	0.3%
自信がない 17374	5.3%

Google N-gram Corpus Counts
╭─ーーーーーーーーー─┬─────┬───────╮
│ 西も東もわからない │ 427 │ 59.2% │GG5, Daijirin; add
│ 西も東も分からない │ 294 │ 40.8% │
╰─ーーーーーーーーー─┴─────┴───────╯

Google N-gram Corpus Counts
╭─ーーーーーーーーー─┬────────┬───────╮
│ 右も左もわからない │ 39.955 │100.0% │
╰─ーーーーーーーーー─┴────────┴───────╯

Daijirin: 
①その土地の地理に不案内である。
「まだ東京に来たばかりで━」
②物事の道理をわきまえない。分別がない。

@@ -3,0 +4,3 @@
+<k_ele>
+<keb>西も東もわからない</keb>
+</k_ele>
@@ -11,0 +15,2 @@
+<pos>&adj-i;</pos>
+<xref type="see" seq="2839896">右も左もわからない・1</xref>
@@ -13 +18,7 @@
-<gloss>not familiar with the area</gloss>
+<gloss>being unfamiliar with an area</gloss>
+<gloss g_type="lit">not knowing west from east</gloss>
+</sense>
+<sense>
+<pos>&exp;</pos>
+<pos>&adj-i;</pos>
+<xref type="see" seq="2839896">右も左もわからない・2</xref>
@@ -14,0 +26 @@
+<gloss>being clueless</gloss>

Entry created

Yes, we don't usually have both tags.

@@ -13 +12,0 @@
-<misc>&rare;</misc>

IIRC [rare] is not used together with [hist], perhaps an editor can confirm or deny.
Though I definitely agree that it's rare, I couldn't spot any relevant non dictionary hits when searching. Has no hits in the kyoto/melbourne or CHJ (日本語歴史) corpora either.
Also not in my 古語 references

https://kotobank.jp/word/寺預け-577043#w-577043

daijs

specifying reference, is also rare

寺預け	No matches

@@ -12,2 +12,2 @@
-<xref type="see" seq="2191860">寺入り</xref>
-<xref type="see" seq="2191860">寺入り</xref>
+<xref type="see" seq="2191860">寺入り・2</xref>
+<xref type="see" seq="2191860">寺入り・2</xref>
@@ -14,0 +15 @@
+<misc>&hist;</misc>

Entry created

Yes, I felt it was really a kanwa usage, although the 開ループ is interesting. I guess we accept it.

This has been sitting for a while, it's really a kanwa entry, but since 簿 is also an entry now this may as well be?

There are hits for 開・かい in BCCWJ among other corpora, 274 to be exact. In which 開 is usually part of a compound or a proper name.

https://en.wiktionary.org/wiki/開#Japanese

As in 開ループ | かいループ | (comp) open-loop

As a literal translation this probably works better. The term was obviously being used in Japan before Costco arrived.

@@ -12 +12 @@
-<gloss>warehouse store</gloss>
+<gloss>warehouse-style store</gloss>

I don't think Costco had come to Japan yet when the ngrams were compiled, implying the current gloss is too specific. Costco calls it stores just "warehouses" in English but that's not a good gloss obviously.

@@ -12 +12 @@
-<gloss>membership-based warehouse-style store</gloss>
+<gloss>warehouse store</gloss>

倉庫店	2736

@@ -12 +12 @@
-<gloss>warehouse store</gloss>
+<gloss>membership-based warehouse-style store</gloss>

Costco uses this terminology

OK. Let's leave it there.
I asked ChatGPT: What does the Japanese term ドン勝 mean?
Its reply (obviously hallucinating):

The Japanese term ドン勝 (どんかつ, donkatsu) is gamer slang that originated with PlayerUnknown’s Battlegrounds (PUBG) in Japan. It’s actually a mistranslation that stuck.

How it came about:

In PUBG, when you win a match, the English message says “Winner Winner Chicken Dinner.”

In early Japanese translations, players jokingly rendered this as 「勝った！ドン勝つ！」 — mixing “勝つ (to win)” with とんかつ (tonkatsu, pork cutlet).

Over time, ドン勝 (donkatsu) became shorthand among Japanese gamers for “winning a match” or “getting first place” — even though it literally sounds like “pork cutlet.”

Nuance:

It has no connection to actual food, though it plays on the sound of tonkatsu.

Used mostly in battle-royale or survival-type games, especially PUBG.

Saying “ドン勝した” means “I got the win!”

I think the note is OK. Having only a generic gloss for this deliberately goofy phrase is kind of misleading and may be confusing without it.

@@ -37,0 +38 @@
+<gloss>victory</gloss>

Apparently not a pun
https://esportstars.io/guide/pubg-donkatsu/
ドン勝は「カツ丼」や「豚カツ」が由来ではなく、意図したダジャレとして誕生したことを覚えておきましょう。

If we don't want to overcomplicate the glosses, I at least like your note as it give some context for why you might use this term in Japanese.  "Winner Winner Chicken Dinner" is an appropriate gloss in e-sports/video-game contexts where this is likely to appear. At least appearing in the note is something.  

It also explains some of the nuance.  So when you see this Redmi Note smartphone ad: 

目指せドン勝。ゲームにも強いシャオミの｢Redmi Note 10｣シリーズは199ドルから
https://www.gizmodo.jp/2021/03/xiaomi-redmi-note-10.html

you know they are referencing the ability to play PUBG mobile on that hardware. For comparison, the article shows the English version: "Redmi Note 10 Series: Challenge for Chicken Dinner"(similarly evoking PUBG, without naming it explicitly).  These only make sense if their audience knows about the gamn. (As I noted, it is/was immensely popular. Wikipedia cites 1.3 *billion* player accounts).

Glossing without any allusion to the game feels incomplete. A news search for ドン勝 will show how strong the link is.

"coming (in) first" looks like it might a regional preference...

@@ -34,0 +35 @@
+<s_inf>from Winner Winner Chicken Dinner in the game PUBG</s_inf>
@@ -36 +37 @@
-<gloss>coming first</gloss>
+<gloss>coming in first</gloss>

I’m OK with that. Might be worth mentioning the pun but it’s pretty obvious.

I suggest a quite severe simplification.
I was tempted to include the following note, but I really don't think it's needed::
[note="from Winner Winner Chicken Dinner in the game PUBG"]

@@ -23,0 +24 @@
+<re_inf>&sk;</re_inf>
@@ -32 +33 @@
-<pos>&exp;</pos>
+<field>&vidg;</field>
@@ -34,3 +35,2 @@
-<s_inf>possibly a pun on tonkatsu or katsudon; coined by the video game PUBG</s_inf>
-<gloss>Winner Winner Chicken Dinner</gloss>
-<gloss g_type="expl">made-up food signifying victory (esp. in FPS video games)</gloss>
+<gloss>winning a match</gloss>
+<gloss>coming first</gloss>

@@ -11,0 +12 @@
+<lsource ls_wasei="y">cassis orange</lsource>

https://kotobank.jp/word/かしすおれんじ-3227579#w-3469110
https://ja.wikipedia.org/wiki/カシス・オレンジ

daijs, wiki

カシスオレンジ	18971

This drink isn't really a thing outside of Japan, maybe wasei makes sense?

Daijirin

GG5, RP
クレームドカシス	2424

@@ -11,0 +12 @@
+<gloss>luggage rack (train, bus)</gloss>

英辞郎１０３; 研究社 新和英大辞典 第５版

Daijisen

@@ -11,0 +12 @@
+<field>&elec;</field>

https://www.ioes.saga-u.ac.jp/jp/ocean_energy/about_ocean-concentration_0
https://ja.wikipedia.org/wiki/塩分濃度差発電
https://en.wikipedia.org/wiki/Osmotic_power
https://www.theguardian.com/world/2025/aug/25/japan-osmotic-power-plant-fukuoka

GG5

NEW斎藤和英大辞典

@@ -11,0 +12 @@
+<field>&ling;</field>

研究社リーダーズ＋プラスＶ２; 研究社　新和英大辞典　第５版

領事事務所	396
領事館	212490 <- more usual term

@@ -11,0 +12 @@
+<xref type="see" seq="1554740">領事館</xref>
@@ -12,0 +14 @@
+<gloss>consulate</gloss>

https://ja.wikipedia.org/wiki/領事事務所

Google N-gram Corpus Counts
╭─ーーーー─┬─────────┬───────╮
│ 両刀論法 │     180 │  0.0% │
│ ジレンマ │ 477.597 │100.0% │
╰─ーーーー─┴─────────┴───────╯
Kyoto/Melbourne N-gram Corpus Counts
╭─ーーーー─┬────────┬───────╮
│ 両刀論法 │      3 │  0.0% │
│ ジレンマ │ 15.600 │100.0% │
╰─ーーーー─┴────────┴───────╯

Sankoku, Shinsen, etc.

@@ -11,0 +12,2 @@
+<xref type="see" seq="1066560">ジレンマ</xref>
+<misc>&rare;</misc>

研究社　新和英大辞典　第５版

KOD

https://www.sand-museum.jp/sazou/
https://ja.wikipedia.org/wiki/サンドアート
https://www.sand-minamisatsuma.jp/about/sand-sculpture.html
https://nanmoda.jp/2019/08/7674/

砂像	6462

gg5

https://www.weblio.jp/content/微細構造定数#goog_rewarded
https://ja.wikipedia.org/wiki/微細構造定数
https://kotobank.jp/word/微細構造定数-119546

Could be either.

Nanzando, GG5, 最新医学大辞典 第2版, LSD

no references submitted

GG5 gives [anat], but I highly doubt a type of cell would be considered an anatomical "part" in the classical sense.
Putting [biol] tag

@@ -12 +12,2 @@
-<gloss>Reticulocyte</gloss>
+<field>&biol;</field>
+<gloss>reticulocyte</gloss>

GG5

@@ -11,0 +12 @@
+<pos>&vs;</pos>
@@ -12,0 +14 @@
+<gloss>excluding foreign ships from ports</gloss>

NEW斎藤和英大辞典

三読会	323
Daijisen

@@ -12 +12,2 @@
-<gloss>third reading</gloss>
+<misc>&hist;</misc>
+<gloss>third reading (of a bill in the Imperial Diet)</gloss>

NEW斎藤和英大辞典

https://ja.wikipedia.org/wiki/イカルド・テンタクルズ

@@ -1,3 +1,2 @@
-<ent_corp type="jmdict">jmdict</ent_corp>
-<ent_seq>2867086</ent_seq>
+<ent_corp type="jmnedict">jmnedict</ent_corp>
@@ -5,0 +5 @@
+<re_pri>spec1</re_pri>
@@ -8 +8 @@
-<pos>&n;</pos>
+<misc>&char;</misc>

Seen in this video around the 1:07 mark: https://www.youtube.com/watch?v=jdLqCJ1zj2U&ab_channel=ちろぴの

Searching "イカルド" on Google will show Squidward