Inventory desync (+ crash) 1.16.5 client on 1.12.2 server

[Eerosal]

Describe the bug, provide any errors Crafting items can sometimes crash 1.16.5 clients and cause desync. I believe this is due to the behaviour difference of the versions when shift clicking items in a crafting table view.

I wasn't able to reproduce crashing but a few players have reported it happening.

Some have also reported that the hunger bar will show a level 1 after crafting attempt when relogging. It did happen to me, but I don't think it is caused by ViaVersion. It still is worth mentioning.

How can we reproduce it? Steps to reproduce the behavior:

1. Login on 1.16.5
2. Take 1 iron block to inventory
3. Open crafting table
4. Move the item to the grid by shift left clickng it

Expected behaviour On 1.16 the shift left clicked item should be moved to the grid, but in older versions it is moved to hotbar.

Screenshots

ViaVersion Dump https://dump.viaversion.com/48c597a93c6ed200aa41131c2ed3b9fd89586eeb8fba1f5ce63fd581e579d820

Additional server info Proxy software: Velocity Server software: PaperSpigot

Checklist

• [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 a build from https://ci.viaversion.com/ and the issue still persists (tested after /viaver dump, no difference)

[FormallyMyles]

I'm not 100% on how we can fix this as we don't track the inventory from ViaVersion (meaning we don't know what slot to correct the action to). It might be possible to do some sort of forceful resync with a crafting table open.