The issue is caused by a slight change in youtube-dl's metadata output.
After a refactoring, it stores the 'adr' value as a floating -point number, but sinusbot expects an integer.
I patched youtube-dl and restored the old behaviour.
You can find a patched executable on github: https://github.com/Clubfan22/youtube-dl/releases/tag/2021.04.01-sinusbot
However, if you don't trust me (and really, you shouldn't just execute any code found on the internet!), you can build youtube-dl by yourself from my patched version: https://github.com/Clubfan22/youtube-dl
I don't plan on filing an upstream issue for youtube-dl because it really is a problem caused by sinusbot and should be fixed with a sinusbot update.