Do you have a reference for that?

I did a search for "Quillette Alt-Right" and I got a ton of articles from them against the Alt-Right, and comparing the extreme Left to the alt-Right.

It's Patreon-supported, is that alt-right too?

It was founded by Claire Lehmann, who worked for the Canadian far-right Rebel Media (RebelTV).

I don’t personally consider it alt-right, but i think someone viewing it that way is totally reasonable given her media background.

RebelTV is not alt-right; it's founder has explicitly disavowed any association with the group/term. (Not to mention all the non-whites and women they employ.)