Tal

BDS/Realms only runs in one language at a time, so if the client is running in Chinese and BDS is set up in English, BDS will attempt to compare the name the client sent with the English name, and since they're obviously not the same, a custom name will be set. This is likely also reproduceable with the integrated server, if you invite a friend who has a client set up with a different language versus your own.

Item name before enchanting:

Item result in the anvil menu (the client's prediction):

Item result in the main inventory (the server's prediction, now has a custom name):

This is likely also reproduceable with the integrated server, if you invite a friend who has a client set up with a different language versus your own.

Yup, just confirmed what I initially suspected: BDS/Realms only runs in one language at a time, so if the client is running in Chinese and BDS is set up in English, BDS will attempt to compare the name the client sent with the English name, and since they're obviously not the same, a custom name will be set.

Item name before enchanting:

Item result in the anvil menu (the client's prediction):

Item result in the main inventory (the server's prediction, now has a custom name):

This doesn't even seem to be Unicode related - BDS seems to only support one language at a time, and any other language isn't properly accounted for by the looks of it. 

(MCPE-154453)

I don't think the cache system is necessarily at fault here, but there does need to be a hard limit to the amount of objects that can be cached client-side, or some sort of expiration after X amount of time. There's likely tons of cached sub-chunks that haven't been used in months on most devices.

— When a player puts an item into the anvil, the name editing box on the GUI of the anvil will show the name of the item itself, but when combining with the anvil, the client will send the name of the item to the server, regardless of whether the item was actually renamed. The server will then decide that the item needs to be renamed and consume additional experience to do so, unless the box above is empty. This bug causes the client and server to have a mismatch when the player creates the item with the anvil, thus causing the action to be reverted.

This issue is likely indirectly caused by how the server authoritative inventory system works with anvils. There is no specific indicator in the CraftRecipeOptional stack request action that can be used to determine if the item was renamed or not; FilterStrings always contains at least a single entry, the FilterTextPacket is no longer sent as of v1.18.30, and the resolved filter string is always either the item name or the custom item name.

Unless the server properly supports every locale that the game supports, there is no way to properly detect if the client intended on a rename or not. This is unrealistic to get exactly right, especially for third party servers including featured servers which may not have mappings for each item and their display names.

Since BDS supports all locales anyway, it likely isn't an issue for it as long as both names are properly compared in a way that is Unicode compatible (likely the issue being seen here) but this is still a fairly major problem for 3P servers. 

Does the bug fix prevents from similar issues from re-occurring, or will it also recover the voids and reinstate the missing objects?