Alt+\ Issue

Hello! I'm having a really peculiar issue which seemingly appeared out of nowhere.

I used to have bound my mount to the Alt+\ key (Italian Keyboard layout), but now whenever I press that, whether anything is bound to it at all or not, my game enters an odd state.

Here are the behaviors I can record:

Firstly, I play in fullscreen, not borderless.

I press the Alt+\ keys and my keyboard stops working. My cursor also is replaced with the standard Windows mouse pointer.
If I left click then the cursor switches to the FF one. I can move around with keys like W or D but any key that is bound to a chat channel switches it to its assigned one. (S goes to Say, F to Free Company etc.)
Any other key that I press (only after I have switched to another channel with the above mentioned) types in the chat as if I had pressed Enter or clicked on it. Rendering me unable to move.
Sending the message with Enter does not fix the issue. The game still behaves as if I were in the texting mode.

If I alt+tab out of the game, then in, the issue is fixed. I can of course just not alt+\ at all... but I'm curious if this is a known thing as I cannot find any info on the internet...

Thank you for the help and time.