You can refer to the video below to test the flatness of the hot bed with a steel ruler and A4 paper.
Please try to apply solid glue (PVP) on the hot bed or stick masking paper, and then print the official test model to observe whether the printer model is normal. If there is still no improvement, replace with a new lattice glass.
(Note: Lattice glass cannot be wiped with high-concentration alcohol)
Please set the hotbed temperature to 70 ℃ and print the test again.
The Build Plate Adhesion Type could be changed to skirt (skirt does not contact to model) or to brick, with a distance of 0.3mm (contact area is small).