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.
Unless you’ve deliberately reversed your walls/infill printing order, the default is to print walls first. Your print head and nozzle won’t have any reason to leave the perimeter of the model even if you’re printing multiple examples of the part until the entire layer is complete on one of them. It will move to the next part in the array only after finishing the infill, which is well after your problem may have occurred on either the inner or outer perimeters on any particular layer.
I’m not sure what you’re on about with top fill. I didn’t say anything about your fill pattern or percentage.