heatbed tests results for marlin G29 T command

After some troubles with printing large objects,
I decided to test my Aluminium HeatBed - and what I see - it bended :(
I use Marlin firmware https://github.com/MarlinFirmware/Marlin
it has ability to use various probes for detection minimal z position,
and best for my mind is an inductive detector LJ18A3-8-Z/BY
after seeking I found G29 T parameter wich can show z points on heatbed
it dumps to console like this vertices and finaly bed matrix

sample rezult for command **G29 T P4**
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