How to recreate:

1. Launch the game
2. Go into the Controllable settings
3. Go to the "Bindings" tab
4. Hover over a setting
5. Witness the following:
   

Solution: Fix controllable-fabric-[version]-[modversion].jar\assets\controllable\textures\gui\buttons.png. Where is it? I mean, just look at this:

Thanks for the report. I will get this fixed 😂

Fixed in c7894d9