I think i found the issue. I had an extension that makes windows always open in the same window (to avoid popups opening in their own window). the extension is not for opera but for any browser. i assume it was reading some of the other workspaces as if they're not in the main window and was moving them there when i opened opera. ihave disabled the extension and so far no issues. will update if the issue continues, but for now, it seems to have solved it. such a relief and makes sense that its not opera itself, as i had reinstalled and deleted my opera folder etc.