Backspace key resets keyboard layout

Hey everyone,

I’m a Debian 12 user, KDE 5.27.5, and I have 2 keyboard layouts which are switched between by alt+shift combination. When I start typing something in my language and click Backspace it resets the layout to English while continue showing my language in the tray. So I have to do alt+shift 2 times to get my layout back.
It happens to some applications like KWrite, Dolphin, Konsole but not to Firefox for example.

How do I debug this issue?

Can I up posts here? This issue is extremely annoying.