Hello @Femi_Allen
First thank you for your report of this bug. As you wrote in your message some users are experiencing a bug about the horizontal bar on YouTube.
This bug was also talked in this subject :
As wrote in the subject, the Dev are aware about it and are into it, but might takes some time to fix it. Youtube changes codes a lot recently
In order to help the Devs, don’t hesitate to give the maximum of informations that you have when you report a bug (using VPN, Which others extensions you have with your Browser, etc…)
Did you try to use an other Browser which support this extensions ?
Have you still the same problem ?
(I’m also learning Korean but I’m using “Brave” as a Browser - which include an ad blocker - and don’t have this problem on YouTube.)
Thanks for your report,
M.D