I've had this issue now multiple times:
If you screenshot something and then tab on the screenshot it opens up the original gallery application. Ff you interact with the gallery application while the preview of the screenshot on the bottom left corner It'll just stays there. You can't swipe it away. Even after closing your phone and reopening it doesn't make it vanish. After some time it'll disappear by itself. I wanted to report this issue. Maybe other people also had this issue.