Items dupe and some other 1.21.3+ issues

[Envqu]

/viaversion dump Output

https://dump.viaversion.com/35d956afce1f49ae26e23ebf843143f99f56b44b683737065898cff7d89f7ea5

Server/Client Error

No response

Bug Description

Hi. Server version is Purpur 1.21.3 but I allow to join with 1.20+ Problem is if player plays on version lower than 1.21.3 then any custom named item if is double clicked glitches when any container is open (normal chest, custom gui) I tried latest snapshots but it still occurs. It didnt happened on Purpur 1.21.1. Edit; it also happens with Purpur 1.21.4

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one more - if player has creative gamemode and he drops any item while their inventory is open and then he picks it up and drops again without closing inventory then item duplicate (in this case it works with regular player inventory, not container) ^ this happens on 1.21, my friend tried that on 1.21.1 and nothing happened

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Also destroy item in creative inventory is broken. If player click shift + Destroy Item then items are removed when player close inventory instead instant.

I also tried with latest snapshot avaiable on hangar without any plugins but cant send here dump, because bot closing issue...

Steps to Reproduce

1.21.3/4 server + login with lower version client

Expected Behavior

No duping

Additional Server Info

No response

Checklist

• [x] Via plugins are only running on EITHER the backend servers (e.g. Paper) OR the proxy (e.g. Velocity), not on both.
• [x] I have included a ViaVersion dump.
• [x] If applicable, I have included a paste (not a screenshot) of the error.
• [x] I have tried the latest build(s) from https://ci.viaversion.com/ and the issue still persists.

[Barvalg]

[Envqu]

Second bug happens only if player has open "Survival Inventory" in creative mode

[Envqu]

Also bug with head movement. There is an input lag visible for 1.21.3+ players while watching player who plays on 1.21 [lower version than server - 1.21.3] (pitch axis, its visible on 1.21.3+ after 2 seconds if 1.21 player not walking but if he walks then its updates immediately. )

[Envqu]

Also weather issues. Its started raining for 1.21.4 player but not for 1.21.3 and lower version players. Its stopped when he rejoined

[BredyAK]

Also destroy item in creative inventory is broken. If player click shift + Destroy Item then items are removed when player close inventory instead instant.

can confirm that with latest ViaVersion-5.2.2-SNAPSHOT-b1078 + ViaBackwards-5.2.2-SNAPSHOT-b550 build with Minecraft 1.20.1 client on paper-1.21.4-b128 server.

[Envqu]

Hi. Anything? These bugs make game unplayable for some players

[Envqu]

Another Issue. Elytra doesnt work if server is 1.21.1 and client is > 1.21.1 (fe. 1.21.3)

[Envqu]

Hi. Any news?