>>3871887Service center called me today and "of course" photos did with X-T3 didn't showed any damage. and "it's hard to judge" by the my photos from phone what's that. And the head of repair department of that center told me that it's an oil mark most likely, and the engineer simply don't need to open the lens mount lid because it's only flex cable of shutter button replacement. They suggested to bring camera to the service center and if it's oil then I'll pay for sensor clean, if it's really damaged sensor they'll order a protection glass and contact Fuji and "maybe you won't have to pay for repair". Just freaking nice. The rhetoric of the service center is passively put the blame on me, as it seems.
I also managed to do other photos where this mark is more pronounced and visible, and there's also some dirt/smudge on the side. The sensor wasn't that dirty before the repair in the first place.
I has an email address for contacting some guy from Fuji from my country, but I really have no idea who is he and whether he'll be able to help or not. I l also found some emails of EU Fuji department, but I'm not so sure that they'll be able to help as well as not sure if it's proper email addresses to address that kind of issues internationally. If anyone knows where I can write to Fuji EU (except the contacting form on their website), I'll be very grateful for that.