Removal of repositories like youtube-dl seems to have been happening for a while though, here are couple of examples:

Removal of Udemy-dl (2015,2017): https://github.com/github/dmca/blob/master/2015/2015-08-12-U... https://github.com/github/dmca/blob/master/2017/2017-11-13-U...

Removal of linuxacademy-dl (2018): https://github.com/github/dmca/blob/master/2018/2018-09-24-l...

Removal of Instagram-API (2020): https://github.com/github/dmca/blob/master/2020/01/2020-01-2...