It is always recommended to double check the Print Settings section of PrusaSlicer if there is an issue with a 3D print.
First Layer Too Squished or Not Adhering
If the first layer of the print is either starting too close to the bed (layer will look very thin and squished) or too high from the bed (may not be adhering to bed at all) you will want to stop the print immediately.
Usually, all that is needed is to restart the print so that it can run through the auto-leveling sequence again.
If restarting does not fix the issue, please notify staff.
Image courtesy of Prusa
Corners Warping / Curling
Photo courtesy of Simplify 3D
Warping occurs on prints because plastic, shrinks as it cools. For more details, check out this page from Simplify 3D. This is especially noticeable for larger prints. It is recommended to turn on Brim in PrusaSlicer to help increase the surface area of the print which in turns helps hold it to the bed. Residue on the 3D printer bed can also contribute to warping, so it is important to make sure the bed is cleaned regularly.
Print Coming Off Bed
A similar issue is prints coming unstuck from the printer bed completely during printing as seen in the photo below.
This is more common when trying to print multiple pieces or tall, narrow objects. Like warping, making sure the 3D printer bed is clean and using a brim during printing may help prevent this from occurring.