Yes it would have been helpful to mention that you’d already done a factory reset
As far as I can see there remain two possible sources for the problem: an error with the OS software itself (including Play Store software), or a hardware problem.
Do you remember a particular event some months ago (from your own indications) after which you started to experience these problems and which might be the cause? Physical damage? An OS update that went badly?
Have you been in touch with Fairphone official support over this?
Is the phone still under guarantee (bought less than 2 years ago)? If so it’s really important to #contactsupport immediately, to benefit from that.
Have you seen any other malfunctions that might be due to faulty hardware (lost or damaged files for instance)?
In the event of damaged OS have you any experience with ADB?
I would also recommend enlisting help on this, either from a local #fairphoneangel if there’s one near you, or else you might find a good repair shop or send the phone in for a repair estimate (if no longer under guarantee).