uneven build plate temperature?

[mhristau]

99% of my Mini2 printing has been within the centeral region of the build plate.
Starting to print a set of calibration cubes, (1 at each corner, centered at + or - 60 xy)
the bottom face peals up warping the print. Is this the result of uneven build plate temp at the extremities? What to do? Common problem? Unexpected feature?

[mwester]

What type of filament are you using?
Do you have an enclosure on the printer?

[mhristau]

Thanks — PLA Polymaker Lite and Matte Forge PLA.
No enclosure... For PLA?

[mhristau]

Finally, I have printed a set of calibration tiles in Lulzbot Green Polylite PLA, .25 nozzle and .05mm layers. Still a warping problem in the back right area:

The attachment tilesTest.jpg is no longer available

[mhristau]

...and 2nd image