As far as I know, that’s just how stuttering is. Fluency can come in waves for no reason kinda like how creativity is. Personally, I notice I’m slightly more fluent when I’m talking as much as possible and working on my techniques every chance I get. When I’m more isolated, (like many others during this time) my stutter tends to be harder to control at times. Bottom line is you’re gonna have bad stuttering days for no reason at all sometimes, and when that happens just do your best to not let it ruin your day.