It’s possible he didn’t like quality of your work so he’s not comfortable giving recommendations. I am not saying quality wasn’t good, but perhaps he thinks that. Otherwise he’d respond that he’s busy or something. No response is telling you how he feels. Plus it’s possible his negative opinion about your work effected higher up’s decision to let you go as he directly supervised you. He can’t possibly write your recommendations.

I also think that remote work creates situation where you don’t really get to know people well, no connections are formed, so he might feel he doesn’t even know you. I am surprised they are 100% remote as most companies have at least part time in person interaction nowadays, unless you are out of state