Your nozzle is too close to the heated bed, possibly coupled with an out of level bed. Shavings in the hobbed bolt may chamber may be further compounding this. To fix.
Step 1: Clean the hobbed bolt chamber to remove all shavings. take special care to remove impacted material from the hobs themselves and from around the bearings on the idler.
Step 2. Heat the machine to operating temperature, then wait 15 minutes to allow for normal operational expansion of the hot end.
Step 3. Using a thick business card that looks nonflammable or a thin metal gauge set the thickness you want at your home point. Now move the nozzle in the Y direction and check again using the gauge or the card as a feeler. take care so as to not burn yourself or light things on fire. Now move the X axis over in 1 inch chunks, continually checking that the height feels the same. if you find a change as you approach one side or the other, adjust the height of the bed plate accordingly. repeat the process to either side of the Y axis as well. Once you are satisfied the nozzle is the same height from the bed at operating temperature at any point on the bed, return to home and print your calibration print.
That should fix it. You may also want to make sure the filliament is feeding properly with the nozzle raised away from the bed to make sure you don’t have any other extruder issues.
Poor quality filliament can also sometimes cause excess grinding if you are using something sourced from less reputable sources.