Fenix 6X - Screen artifacts (shadows)

Recently I noticed that there are blue "shadows" to the right of white elements on black background. Mostly visible on white minutes.
I can seee them also on widgets, so this is not just a watchface problem.

When I cycle through activity screens (white) they disapear, but slowly reapear with every screen refresh.

Is this is this hardware or software issue? I restarted the watch and tested on different watchfaces (build in and IQ)

It is on 26.00 firmware (non beta)