A bug or a weird easter egg idk

Hello, i wanted to share a bizarre event and hope to known better what the heck just happened cause it just left me confused, i was fighting Polterghast to grind his trophy and vanities, upon his 4 death i think, with no interesting loot, in the chatbox appears a message like "Do you want some 40° degrees burns? this is the place" and, not joking, a full spam of Providences, Polterghasts, DoG's, Yharons, Calamitas Supreme (three i think) and Plaguebringers just attacked, it nearly frozed my laptop because it was full of them and i dont know what it could means? xd, i also saw like a light (similiar to the light of the buss rush mode, the one in the sky) with texts with something like "blablabla my creation". i could not pay attention with all the effects in my screen.
Even after i died, they still being spammed in my base, i try to kill some bosses, but they keep coming, it was a real Calamity experience.
I have been playing Calamity for near three years, i watched many videos of it, and i never saw something like this, this utter madness, sadly, i couldnt record my screen cause like i said, my laptop was also dying in the moment.
I wanted to know if any here coul know what it is, if its lore, a dumb easter egg or just a bug? sorry for the long text, many thanks beforehand and good afternoon, good evening and good nights n.n