Every Sync Must Be Forced, Normal Sync Results in Error 400

You have bad data in your collection, probably from an add-on you used about a year ago. The following in the debug console will remove it, and then you’ll need to upload to AnkiWeb.

mw.col.db.execute("delete from revlog where type > 4")
mw.col.modSchema(check=False)

https://docs.ankiweb.net/#/misc?id=debug-console

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