Is your feature request related to a problem? Please describe.
Not really a problem, just a small inconvenience. Sometimes when I go back and modify tag/label filters (i.e. "apply label" filters), they don't get applied retroactively. If I had a typo in the filter, there seems to be no way to re-run the filter on all saved feeds to apply the label to those (now) matching.

Describe the solution you’d like
Honestly I don't think this is something that needs to be done often, so a simple utility like those in cli/ that could be ran and perhaps also a button somewhere in the UI (just like refreshing feeds is possible in multiple ways) that re-scans the database entries and applies label filters to them, and applies the label if filter matches.

Describe alternatives you’ve considered
Unfortunately do not see any other alternatives, except perhaps using user queries (I believe the results of those are not persistent in the database hence defining a filter and running it would rescan all the entries, but that's pretty expensive).

Additional context
I believe there is no other context I can provide, I hope the explanation is clear. If that feature is hidden somewhere already, I apologize, I could not find it.