GPS is not accurate and slow

[fidelis]

Have you tried this:

GPS lock takes minutes after 4.0 update (is A-GPS working?)

I checked AGPS on FP4: I don’t see any problem, GPSTest shows a long list of satellites in less than 2 seconds. Maybe you should refresh the data: install GPSTest from f-droid, and clear assist data.

This solved it for me (S10+).