Hotkey for fourth hotbar slot does not work while holding spacebar

I think this is probably a hardware issue rather than an issue with Minecraft.

This is likely due to the way that the keys on your keyboard are connected, or something similar.

Can you check if this also happens outside of Minecraft, or with another keyboard?

The "4" key works as intended while holding space outside of Minecraft. However, the hotkey also works as intended when using another keyboard.

What keyboard are you using?