I have had bad, wet sections of PLA refuse to adhere to beds or its own layers. There’s a lot of ways a filament manufacturer could fuck up the blend or moisture control, especially with cheaper shit.

Cut a section out and hold a lighter or heat gun under the end until it softens and curls up.
Good filament should look smooth and the same color. Bad filament will get bubbly, wart-looking texture and take on a yellow sheen. The bubbles are moisture leaving the plastic and the yellow sheen is the plastic breaking down, it will have no adhesion.