Cups has been forked after Apple supplied only one commit in all of 2020 Posted by quazeekotl on Thursday October 15, 2020 @09:23PM from the github.com dept. https://github.com/OpenPrinting/cups ( 1 comment | 4 points | on HN )
Completely understandable to move the upstream repo away from Apple, I don't think there's much else to it. He's been very active in the fork AFAICT.
His Sponsors page: https://github.com/sponsors/michaelrsweet
[1] https://github.com/apple/cups/graphs/contributors
[2] https://www.msweet.org/blog/2019-12-20-left-apple.html