I have a Creality Ender 3 V2. I have done quite a few prints with it using only PLA. When the prints are done, there is always a bubbly looking ring around the bottom of them. I have tried using rafts, and changing slicer settings to fix this and nothing has worked. Are there any ways I can try to fix this?
Something is wrong with your bed height, Z axis mechanics, or "automatic bed leveling" if you're using that. During this section of the print, the nozzle is not accurately at the requested distance from the bed, and material is spewing out to the sides where the printer tries to print the next layer too close to the previous one.
Try using the printer controls to manually move the head in small increments around 0.1 or 0.2 mm, and measure that the distance between the bed surface and gantry changes by the expected amount each time you move. I expect you'll find that it doesn't.
We'll probably need further information to track down exactly why it's not happening.