What a debacle. If GitHub believes this is necessary to comply with sanctions, they should provide a "rather than shut me down, please block contributions that GitHub would consider sanctioned” switch.
Can’t speak for others, but I for one wouldn’t want this switch, and would be offended by it. I would defend people’s rights to contribute to open source regardless of their nationalities by taking my project elsewhere.
Then you'd probably still want this switch, but expect to be notified of the block. Then you could move in an orderly fashion.
Then take the project elsewhere but the leave the switch
Where can I read about the guidelines that "contributions from certain people break trade sanctions". Am I reading that right?