Closing (flatpak) Mailspring fails and eats all CPU

[tomastan]

Actually this is not Flatpak related, the same happens with RPM package for me in 1.19.0.
Same issue reported later by another user:

The program's background processes continue to run even after it is closed

Description I encountered this issue on an Arch Linux KDE Wayland system. When closing the program, the system error message shown in the image appears, and the program’s processes continue to run in the background. Every time the program is started and then stopped, the running background processes multiply and can consume all available memory. Screenshots [Képernyőkép_20260316_103554] Setup OS and Version: Arch Linux Installation Method: AUR Mailspring Version: 1.19.0 Additional Conte…