ERROR message: how do I fix this :(

I downloaded a shared deck. The advice of those who created it was to downgrade to an older version for it to work and it didn’t. The other fix was supposedly opening the deck of cards under a new profile also did not work. I tried turning off the add ons and also… failed… Below is the error I get with a bunch of links after that. I would appreciate help so much.

Invalid HTML on card: ReferenceError: separator is not defined
ReferenceError: separator is not defined