Hi, i'm not sure how long this mark has been here, it's only visible on certain, lighter backgrounds / apps.
It doesn't present itself on screen prints either -- What is it & is it repairable?
The blob? If that's what your referring to and a screen shot didn't pick it up then it's hardware related. There was another post with the same thing. It turned out to be a failed display due to moisture if I remember rightly.
Yes, poorly glued crystal/screen assembly has allowed water to leak onto the OLED. For some reason the top right seems to be the area that fails the most often. Replace under warranty.
I had the exact same thing at the same spot. Probably due to moisture the OLED pixel are dying. For me it quickly continued spreading over half the display. Got the watch replaced under warranty