Yes, right-clicking (well, spell checking in general) has been a bit unreliable ever since macOS 14 came out. There is a thread on that over here. We’ve done what we can to minimise interference, but at this point we’re running at about as reliable as the core system (like in Mail, TextEdit, etc.) itself—which isn’t itself 100% reliable. Of course one tends to notice problems more in software where tons of text is being worked upon heavily, than in Messages or Notes or whatever.
The dialogue window is the steady and reliable workaround, if you run into problems with right-clicking on red underlines.