Hey, thanks for the report. This is a known issue. The update service on Linux doesn’t check what format you installed and always suggests AppImage.
Related thread with the same root cause: Linux `.deb` / `apt` installs get a non-actionable update popup before the package exists
The team is aware. For now, the workaround is to set Update: Mode to none in Settings Ctrl+, to hide the popup. You can update via sudo apt update && sudo apt upgrade cursor as usual.
Let me know if you have any questions.