About half the time recently when printing with PLA, I see that holes or loops have a line of filament running approximately through the middle which seems to be one of the inner perimeters having detached and contracted, but is still attached on both sides. Is it a temperature thing, an extrusion thing? I can’t find a pattern. Bed adhesion is great. Bambu H2C, mostly printing with Bambu Basic PLA.
That looks like multiboard snaps. They are specifically designed for 3 walls, .2 layer height and .4 nozzle.
I had problems that looked like that from z hop. The nozzle was dragging. Enabling zhop (or increasing it a tiny bit) can stop the print head from dragging and leaving filament wisps.