In GNOME Software I sometimes see a warning that an app (usually from Flathub) has stopped receiving updates.
How do you evaluate when, or whether, an app is problematic because it is no longer receiving updates?
In GNOME Software I sometimes see a warning that an app (usually from Flathub) has stopped receiving updates.
How do you evaluate when, or whether, an app is problematic because it is no longer receiving updates?
Some - yes. Others - no.
If it’s an internet-facing thing, it probably has security holes in it, so a trickle of fixes is reassuring.
If it’s a game, it might just be complete, finished and done (think chess), or it might get occasional content updates (moar different kinds of swords!) or it might get the occasional bugfix or a port to a new platform.
It’s OK, in my eyes, even desirable, to be feature complete, and to have no bugs.
Software is never finished, because the entire eco system is evolving. It could be problematic, if the libraries it depends on changes and the program doesn’t work correctly or doesn’t start. In worst case vulnerabilities need to be patched could leave a door open to be attacked.
If it’s an internet-facing thing, it probably has security holes in it, so a trickle of fixes is reassuring.
Offline tools can have security issues too.

If it’s connecting to the internet - Yes
If it’s fully offline - No
If it’s fully offline - No
Offline apps can be hacked too. Otherwise there wouldn’t be a reason to update offline apps at all, when a vulnerability is found.
You’re delving into the unpleasant realm of risk assessment. How likely is the app going to be targeted by a threat actor, and how badly could they use it to damage your data or system?
If it’s a public facing service, I’d immediately check if I have alternative applications I could migrate too. Any hold an outsider gets through the public facing app could be used to pivot further into my network.
If it’s something that doesn’t interact with the network at all, then I wouldn’t worry nearly as much, but might look for alternatives any just because I know this isn’t going to get improved at all. Somewhere in the middle, you need to decide how much risk you can accept.