Corner lifts and wrinkles
I have only been 3d printing for a few months now since I've gotten my first 3d printer, but occasionally on larger surface area prints, I get bending like this and it wrinkles up.
I thought it was poor bed adhesion in some areas after printing for a while on the smooth sheet, but even with cleaning it properly I would still get this, and its now happening on the new textured print sheet I just barely got that has no prints on it at all.
Only used PLA filament, different brands, different infill settings, and still no luck at a permanent solution to this.
This is warping due to thermal contraction as the extrusions cool. It is pulling the corners from the print sheet; in extreme cases it may even lift the sheet away from the magnets.
Protect the printer from drafts (including AC outlets.)
Use a brim and perhaps 'Helper Discs' - Prusa's version of 'Mouse Ears' which are easier to look up.
Use an infill pattern that does not stack long, straight, extrusions on top of each other.
Consider introducing cuts or grooves in surfaces/perimeters that might generate the greatest stress to break up the forces. Like this:
In extreme cases consider annealing the part post-printing.
Cheerio,