Please try automatic leveling again. After the leveling is completed, compensate the Z-axis distance during printing and adjust it to the effect shown in the figure below. The larger the value, the further the distance between the nozzle and the hot bed; the smaller the value, the closer the distance between the nozzle and the hot bed.
You can refer to the video below to test the flatness of the hot bed with a steel ruler and A4 paper.
Video link: https://www.youtube.com/watch?v=bJiJJn7Ybf8
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).
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, you will need to purchase a new hotbed assembly.