burnspot
After 9 months I just changed the nozzle on a anycubic 4max, re-leveled the bed and got good adherence.

However, with three difference filaments I last purchased I am getting what looks like burn spots in the prints and sometimes there will be a small glassy ball of cooked filament stuck to the side somewhere.
I suspect thee are microscopic bits of filament building up on the nozzle and these get heated for a long time and "dumped" every once in a while.