I bought recently a FP4 as on the second hand marked together with the original case. The phone and the case are now 2 years old. I have the feeling that the case does not fit very well (anymore?). It is very easy to get the phone out its case and at the top right corner is so few force needed that I guess it would just slip out of the case if dropped on the screen.
My question is if the case does lengthen over time or if this is the regular state. I also added a picture which shows hoe the case does cover the top right corner of the phone.
My case is also 2 and similar to yours, but not quite as bad. I just take the phone out of it, and bend the case a bit into shape, and it’s never given any trouble with the phone slipping out. I just bend the edge itself, right around the corner with a bit of pressure. I don’t bend the whole case, or the back.
the official case for the fp4 is pretty bad and notorious for not fitting well. And it just keeps getting worse over time. I also have the case and the phone is really loose in there. I can flick the case off the phone with a finger. Still it protects the phone against impacts to the side or back pretty well, the front and screen not so much. If you don’t have already I suggest getting a glass screen protector. If the phone falls and lands on the front, the case won’t protect the screen, the screen will hit the floor.