une recherche sur ce theme m’a mené sur https://www.reddit.com/r/Fedora/comments/17ra7j5/comment/k9218ud/
Dans son cas il semble avoir trouvé la cause
The compose key! Sometimes I have to write accented letters and I use the compose key to type them. The key assigned to the modifier is not physically present on the laptop and it causes the weird behavior. Setting it to a key that it is present resolves all issues.
Bon je ne connais pas la compose key, mais c’est surement une piste a suivre