worn out screen surface [answered]

I have exactly the same issue, only that on my phone that "worn out zone" is on left side, and is not spreading. I didn't use any kind of screen protector.

Well, the zone is bigger than the first time I saw it but it is stabilized for now. Not spreading anymore. And maybe the screen protector has nothing to do with it and it just prevented that I could see it until now.

so does Jolla recommend retaining the original screen protector or is it just a packaging film that is expected to be peeled off before first use?

As long as I know there is no recommendation by Jolla either in favor or against keeping the original protector. I would say it is expected to be removed but there are people that have kept it until they buy a proper protector. Anyway, as Kreso said, he has not used the protector and has the same problem so probably it has nothing to do with the protector.

I have the same problem with my Jolla, on its left side, as Kreso. If the phone is cleaned from fingerprints with a soft tissue, the surface is clean and seems homogenous. But if one swipes over the affected area, the difference can be seen: here it looks smeary, unaffected areas are mostly clean ( very litte smear visible). The differnce can also be seen when breahting upon the screen, it's not homogenous, the affected area can be seen. I did not use any cleaning supplies except a wet tissue..