The anki version that comes with Debian buster also has this issue. It might be worth checking out in bullseye if the problem exists as well. If it does and we find some fix for it, then that could probably be backported to buster as part of updates.
- Bug#947388: anki: Ctrl+Enter not working in Debian Buster KD... Rahul Amaram
- Bug#947388: anki: Ctrl+Enter not working in Debian Bust... Julian Gilbey
- Bug#947388: anki: Ctrl+Enter not working in Debian ... rahul
- Bug#947388: anki: Ctrl+Enter not working in Debian Bust... John Scott
- Bug#947388: anki: Ctrl+Enter not working in Debian ... Julian Gilbey
- Bug#947388: anki: Ctrl+Enter not working in Debian Bust... Julian Gilbey
- Bug#947388: anki: Ctrl+Enter not working in Debian Bust... John Scott