Evidence of a warped build plate?
It looks like your first layer is way too close to the bed. The printer is trying to squash the plastic down very thinly, resulting in inconsistent extrusion. You will likely see better results if you move the nozzle away from the bed a little bit. Increasing the thickness of the first layer might help as well (this is a setting in your slicer).

Keep in mind that if you're trying to print (e.g.) a first layer with a thickness of 0.05mm then a 0.025mm variation in the height of the build plate will result in very strong variation in the thickness of the extrusion on the first layer; in some places it will only be half as thick as in other places. If instead you used a 0.2mm first layer, then the 0.025mm variation barely makes a difference.