I don't know anything about that (I didn't know what Warp was until yesterday, still kinda don't know, as it seems to be a terminal plus AI and I don't know what that actually means). But, alacritty's license seems to allow proprietary forks.

The license requires copyright notice to follow the code and that seems to be present: https://github.com/warpdotdev/warp/blob/6d7a01cc9727472a1bcb...

I dunno if they adhered to the license previous to open sourcing, though, as you have to include it somewhere in the actual binary distribution, as well, and some folks don't do that. And, that's also shitty and unethical.

But calling it OpenAlacritty would be worse, which is what happened here.