1) Test/demonstration of a DDOS against a random target.
2) Attack against a project hosted on sourcehut to make it unavailable (there was even the speculation of disabling a master repository so an end-user could not check that his own local version was the correct one, thus using it with a security hole or a trojan)
3) Attack against a page hosted on sourcehut (I joke that someone wrote "Putin = Fag" on his sourcehut hosted blog).
4) What else ?
So, to me, this is quite unlikely.
I'm actually serious there - school/university holidays invariably bring with them a shitload of fairly random DDoS attacks aimed at ... whoever the attacker feels like.
I don't understand and I don't know where they get that volume of packets from, but I've seen it happen a quite sufficient number of times over the years to consider it as a possibility here.
(excuse the vagueness; if you're ever at the same conference bar as me you're welcome to follow me outside when I go for a smoke and ask for the full story then)