I've been curious as well, I thought it could be a brush a touch up artist or something among those lines used but I could be wrong
i did some searching and it could be a UI navigation button (idk what that is)
Putting myself in the comments so I get notified once someone explain
i looked over korean raws. there's nothing there, so mostly likely some ui stuff from when the translator is screenshotting the raws.
can someone tell me wtf is that black circle with white dot in the middle that i’m seeing in almost every manhwa