Strange camera behaviour stuck and blurred on photo mode

have a very weird bug with my iphone camera. The video makes it easier to understand, but basically :

When I start the Camera app, the image is stuck and blurred. However, if I switch to video mode, the blur disappears. Then if I go back to photo, blurred again. I have to switch to time-lapse and back to photo to make the camera work.

Also, when I try to switch from front to rear camera, it doesn't work in Photo mode, only in video and time-lapse modes.

I've changed the front facing camera but it doesn't fix the problem, and I'm pretty sure changing the rear camera wouldn't change anything.

Any idea what is causing this problem? Do you think it's a software issue?

Thanks!