Because the hotbed is made of metal, the level tolerance is +-0.2mm which won't affect printing if you finishes the leveling adjustment correctly. Firstly, please confirm you have finished the leveling adjustment as below steps:
A. Put a paper on the building surface.
B. Adjust the gap between the nozzle and the four corners of the hotbed by twisting the balance nuts, to make sure the nozzle could press on the paper. If the paper could be pulled out with a little blocked but isn’t scratched, it means the gap is proper.
C. Try to print the test model in the TF card.
After the above steps, if there is still any problem with your printing, please provide some clear pictures of the failed printed models to SELLER for reference. We will provide a further specific solution to solve your problem.