I was working on video like this one:
I’m studying Ukrainian. So I’m not interested in french words.
I have press by mystake the complete lesson as I though there was one page after the one I was studying.
It added around 160 words to known. It made the whole counter of known word meaningless.
There is no confirmation requested.
There is no easy way to revert that manipulation as words cannot be distinguished for words with a definition.
Finally I rechecked the whole lesson word by word to remove them. It’s really tedious.
Sometime I also study 30 minutes video way above my level. I only look for words I can recognize. Once I have completed more than 40% is still blue and must NOT be put to known.