You photo unfortunately doesnt give any context on where this occurs on what screen - but ES File Manager could be the culprit as it has been know to create on-screen popups. Try removing that app and see what happens.
It is from ES File Explorer, they call it floating icon, can be disabled somewhere in settings. In theory, clicking on it gives you ability to take a screenshot, mark something, etc, but I couldn't figure out how to activate it on the TV set.
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