Konsole, backspace, UTF-8

When I use Konsole and press backspace when entering UTF-8 non-ASCII text (Cyrillic in my case), weird characters appear in the input that the program I run gets. They cause Python programs to crash, being unable to process the encoding. If I just do “cat > qqq” and use backspace, I get characters like this:

[mramendi@ramendik-2021 ~]$ cat > qqq
пеф [backspace was used before the last letter was entered]
[mramendi@ramendik-2021 ~]$ cat qqq
пе�ф

The problem does not happen in the XFCE terminal on the same machine in the same KDE Plasma session.

Please advise what to do to fix - or if I should raise a bug.

Fedora 41
Konsole 25.04.2
Plasma 6.3.5
locale en_IE.UTF-8