Developer burnout? Any alternative? Cross platform, Android/GNOME/KDE/iOS. Not sure I can help & donna wanna complain.
So, the Flatpak of Simplenote was apparently maintained by a volunteer, not the developers themselves. And there wasn’t an update to it in the last two years.
The best course would be if the developers would be taking over the maintenance themselves. That being said, they have said they would not.
So you could try to argue for official maintenance (but please in a polite, not demanding way).
You could also look into updating the manifest yourself.
The manifest can be found here. And its a configuration file on where to load the sources and how to build them. Even without deep programming knowledge it should be possible to look into updating them.
So you could make a Merge Request which updates the manifest to use a new runtime version (version 25.08 should be the newest) and with updated sources.
If the Merge Request is fine a maintainer or the Flathub team could then merge it and update it.
The whole project is in maintenance mode & not actively developed. I have migrated & imported my notes to Notesnook. They have a Flatpak going forward.