As I currently stumbled upon a Z tilting issue with my printer I cannot say enough how important it is to have the correct measurements of the Z joints and probing points!
This is often not the case if the tolerance values increases and the probing values differ too much.
At first carefully read through here:
This will hopefully make you familiar with the coordinates of a 3D printer.
Especially what 0,0 means (nozzle position)!
Then again measure and properly define your stepper minimums and maximums!
If an axes homes besides the bed or in front of it then the respective minimum/endstop value can be negative!
From the correct 0,0 point measure the X and Y coordinates to the bed joints (green dotted lines in the next photo).
That is not where the motors are mounted but where the bed is connected to Z and can rotate around it to some degree:
This has to be measured as exact as possible for all three joints referencing to 0,0.
Then depending on your used sensor/probe you choose your probing point as near to the joint points as possible.
For inductive probes stay on the flex steel plate and maybe incline your probing points a bit for safety reasons.