Deletes the whole line instead of a single last letter

I was in the bullet point mode typing my text and as I wanted to delete the last letter of a word, it went on to deleting the whole passage instead. When I undid it (cmd-z), it showed that the whole passage was selected (automatically I guess since I didn’t do it myself). I tried several time but it kept on behaving the same way. Impossible to delete the last letter of my sentence without having the whole thing deleted instead. I have no idea if it’s a bug or a wrong manipulation on my part, altough I am sure I hadn’t selected the whole passage and pushed on only the delete key (it’s the backward arrow with a cross in it, not the delete key per se). Shift key wasn’t on either.
If someone can point to me at the solution, I’d appreciate it. I recently moved to Os Ventura, maybe that’s a probable cause, maybe not.