G35 Assisted Tramming,corner that is used as the reference measurement always lower

I have activated Assisted Tramming in the advanced configuration file for Marlin 2.0 for my Ender 3 V1.


After levelling my print bed with G35 (assisted tramming), the results say that each of the 3 other corners are 0.


I have chosen the reference corner to be front right. After doing this and then running G29, I notice that the front right reference corner is always lower than the rest of the corner.


It seems that although Assisted Tramming is intended to level my bed and it says my bed is level, it actually is not. I have attached a my mesh after using G35.


Why is the front right corner always lower?