Anxiety is not a rational thing, in the same way a friend of the family who had OCD would lambast me about the "particles" my outside shoes and the hems of my pants could bring inside all the while ignoring the giant stack of molding dishes in the sink.

It's a feeling in the body, a sense of alarm. That sinking pit of adrenaline.

I don't think I have autism but I do get ptsd type stuff occasionally.

Interesting observation in the last bit, research indicates links between PTSD and symptons often associated with autism: https://neurodivergentinsights.com/ptsd-and-autism/. That said, PTSD is treatable to a point, if you can verbalise what situations or what experiences cause your ptsd type stuff, treatments like EMDR may help for you.

I'm not sure I disagree that anxiety isn't rational. Anxiety about certain topics may be less rational, but being too anxious to sleep alone in the dark in the jungle likely has some evolutionary benefits. Similar with the anxiety at seeing large predatory animals or the lack of food leading into winter. It becomes a dysfunction when the anxiety is caused by everyday innocuous things to the general public.