I set the back slot hotkey to z and belt slot hotkey to x, but every time i restart the game the belt slot hotkey will be added by a shift key and became shift + x, even its only have x key in options.txt

since I'm using the amecs api, I'll ask the mod dev how to fix this ;)

Can't reproduce the bug, probably a mot incompatibility. You can check it with only installing this mod and nothing else

Problem even exists when this is the only mod installed, step to reproduce:

1. change the belt hotkey to any key without shift modifier (example: x)
2. close the game (close it completely, not return to title)
3. start the game and the hotkey will become with modifier shift (example: shift + x)

Followed your instructions and key doesn't change. Which version do you play on?

Minecraft 1.16.3
Fabric 0.9.3+build207

ok, the problem solved after i added amecs into mods, its required but not mentioned in description

Mh at least that fixed it for you :) otherwise it is already implemented so no need for extra downloading it