It seems like for some users, some textures and other resources have not been updated properly. This is probably a launcher issue instead of an issue with the game itself. For more information, see MC-165967.
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I'm not experiencing this issue myself.
This issue cropped up occasionally after certain updates for some players who then reported it to the MC project.
I'm not sure what the cause of this is, but to me it seems likely that it's on the Launcher side and not on the game side. Hence I cloned it so that the launcher team is aware that this is affecting a lot of users.
The recent snapshot appears to have this issue, or a similar one as well, see MC-250924.
It seems like the launcher sometimes fails to update existing asset indexes or fails to redownload them when they're changed, hence it seems to appear predominantly when updating one snapshot to another. But I also haven't been able to investigate further since I haven't been able to reproduce myself.
Apologies for the late reply, didn't notice that this was closed.
Hello!
As the workaround is mentioned by the [Mod] DrownedZombie in MC-165967, could you try to follow his guide and see if that works for the issue?
Also, try to delete the Launcher and all of the associated files - from the Recycle Bin as well - and reinstall the Launcher. Maybe this could help.
This ticket will automatically reopen when you reply.