This question from your older topic still stands …
See sdcardguide for more info about it, it’s important.
Apart from that, since you have the phone for a while already, strange problems might appear or accumulate. It happens.
The important thing to have now would be a backup of all your important data. Once you know for certain that you would not lose anything important on the phone, a factory reset or installing the phone from scratch would be available as options to try to fix such issues.
https://support.fairphone.com/hc/en-us/articles/360018747238-FP2-Back-up-restore
https://support.fairphone.com/hc/en-us/articles/360018608377-FP2-Erase-all-data-factory-reset-
If you happen to have fairphoneangels in your vicinity (see angelsmap), you could ask whether they would be able to help with any of this in person.