alt+numpad stopped working also alt+ other shortcuts changed behaviour

I dont know what happend ,yesterday i was using android studio normally , i did not restart my computer today i tried to use alt+64(numpad) which should be @ as im used to it and it doesnt work anymore i havent changed anything i tried setting my keyboard layout to 105 generic did not help , i reset every shortcut config to default i installed different keyboard languages and switched over and tried did not help i rebooted the computer 2 times. I have made a update a couple days ago it is possible that it was caused by it but i cant say defintely , what i can say i have not done anything intentionally to cause this , and the only software im using is chrome , firefox , android studio , webstorm , terminal , thunderbird , telegram , signal , ksnipp . Any ideas what to search for , what to try ?

Some sample current behaviour :

The current alt+64 behaviour is as follows : when i press it in the console it does not do anything visible … when i press something else f.e. 6 key again without alt after that i get the output as if i were pressing f.e. the 6 key a long time

if i press alt+4 and then i press 2 shortly after i get 2222

alt+64 and pressing 5 after

this is in zsh console in f.e.

in chrome i get alt+6 behavour switchting tabs the 6th tab alt 4 the 4th tab but i cant write a @ symbol

in kate with alt+64 i get 64

That has never worked in GNU/Linux. Alt+number is an MS-DOS thing that was inherited by MS-Windows.

There is a method for typing Unicode characters in UNIX by using their Unicode sequence — see the link below — but it’s not the same thing, and it doesn’t work out-of-the-box in qt-based applications.