@Zanna I've cast the final OT no-repro vote there. It was with slight reluctance, because the answer does suggest that the problem is Xfce-specific and that it can be reproducibly avoided by switching to a desktop environment. But people who arrive at that question with a similar problem will not likely know that their problem is the same, and trying a different DE is a common enough troubleshooting step that it will likely occur to them anyway.
It's too bad the recent meta question about how an answer can be older than the question it answers was deleted. Merges happen with some frequency, and I'm sure this is something many people have wondered about.
The previous comment is a false positive because Olga Strizhenko admitted to being the engineer responsible for the spellchecking subsystem in JetBrains products in her answer, so her links are legitimate.
