Help to identify mark on the X-T3 sensor (appeared after warranty repair)

[verstovsky]

It lowkey looks like a micro scratch. But it's not easy to see, you can see it only under certain angle and lighting. I've tried to look that closer with a magnifier etc, and have really no idea what's that. Problem is that I'm from Russia and authorized repair service center want to passively put a blame on me. That's not the Fuji's fault, it's the particular regional service center. The sensor wasn't even that dirty before the repair in the first place. There's also visible smudge on the right side, and also two more horizontal scratch-like marks more on the left, almost in center area of the sensor, but it's really really hard to see and I noticed it just by pure luck with a magnifier.

The head of that service repair center told me to take pics with closed down aperture and focus to infinity, which I did (f/22), and there's no visible traces, but yet mark is there and tbh it doesn't matter if it affects image or not, I bought the camera July 21st 2020, it's quite new. He told that it could an "oil mark from the shutter". I'm not a specialist and wanna ask people what it could be, if it's possible to somewhat identify by photo and video. The service itself is a joke, but it's a whole another story (i'm quite depressed because all of that by now).

The repair was flex cable of shutter button replacement, and as I've been told in that service center, you don't even need to open mount lid for this kind of repair, but I dunno, maybe they accidentally did something not during repair, but during diagnostics. 

X-T3 users, maybe if it's really oil mark or something, maybe you or just anyone familiar with that kind of traces? Thanks for any hints.

Here's video :

 

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