What you are doing: adding the unstable repository to your Debian system. Debian has three levels of software stability, stable, testing and unstable.
Stable does what is says on the tin. It’s stable, but older. Testing is gonna be the next major version when it’s deemed stable enough to be called stable. Unstable is for trying out new shit and seeing what breaks. It has the most recent packages and the most problems.
Stable and testing will be named after different characters from Toy Story, unstable will always be named after the character “Sid” from Toy Story.
In the context of what you’re trying to do, you are fucking up.
Yt-dlp can (and should in most cases) update itself by using the command “yt-dlp -U”. But it will only update itself that way if you manually install it from the git page.
You can do this by downloading it and putting it somewhere in your users $path. This is just like putting a program folder in windows in c:\program files and making a start menu entry manually, except you won’t make the start menu entry because your shell will always look in $path to see if it can run what you just typed. If you’re familiar with Macs, it’s literally like copying the program to your applications directory.
There’s instructions how to manually install on the yt-dlp git.
You should do yt-dlp this way unless you have a good reason to use the Debian repos or pip.
E: once you get yourself straightened out, make sure to add “yt-dlp -U” to all your scripts before they actually run. It keeps you from getting the wrong quality profile or downloads from failing or whatever.