It's impossible to get rid of the annoying notification on YouTube (Register for free to translate in subtitles in Netflix, Amazon Video, and others). I'm registered and logged in all the time. In personal cabinet there is no way to disable this add-on for specific sites. Support ignored my message, apparently they are aware of the problem and do not want to fix it. So, I will look for a more user-friendly add-on.
Upd:
I found in the reviews a complaint about the same problem and feedback from the developers "Unfortunately we couldn't reproduce this error. Could you please provide more details?" 3 years ago :) Apparently, they are still trying to reproduce this error.