Same for me, I assume either YouTube updated their system, or, the API has reached it's limit.

Actually I changed the API key and it still doesn't work.
It's a shame because I've used this script for years, worked wonderfully.
Truly indedbted to the author for years of trouble-free use.
Hopefully the script can be edited so that it functions again.
All the best !

I changed Api and its working fine now.

Same code, only api is mine.

Before change i added /msg #channel . %sockreader

I saw:
. "message": "The request cannot be completed because you have exceeded your \u003ca href=\"/youtube/v3/getting-started#quota\"\u003equota\u003c/a\u003e.",

With new Api key:

02:20:55 <@Mrmot> https://www.youtube.com/watch?v=iMaHFAEwMs0
02:20:56 <@Nemirna> YouTube Title: Hot Since 82 & Rudimental - Be Strong (Official Lyric Video) Views: 79,516 Length: 4:06 Uploaded: 2020-10-16 User: Hot Since 82 Likes: 3,402 Dislikes: 41

Could you show where to add this info in script?

Thanks for the update all! Yes, I believe this API key was left unrestricted and has now reached its limit. Thanks for finding the fix @Mrmot. @kamilo23 please change this on line 9

from alias -l yapi { return AIzaSyBZFSgBuREDKNRwHqvHix68W3WiMyZ3N6c }
to alias -l yapi { return YOURAPIKEY }

Ok, thanks