[pea]

Exactly same experience here when I was about 14, from a single time taking mushrooms.

Like the OP, I was convinced at the time I had some irreparable damage, as I was so seeing after-images and static on walls and felt extremely disassociated/anxious, but it was probably more garden variety anxiety than I admitted at the time. Constantly fixating on your thoughts because you think you're losing it is enough to make life pretty stressful. I got therapy and slowly forgot about it.

I still have some HPPD symptoms, but interestingly those (and the anxiety) only started after I began looking for them after reading about them online a week or two after the incident, so I've always been curious if anyone can turn off their brain's filter enough to notice them if they tried.