There are two types of possible causes for corner curling, if the corner curling occurs in the early stages of printing then it is likely to be due to the adhesion problem of the bottom bed, if the corner curl occurs in the late stages of printing then it is likely to be due to overheating problems.
For the problem of overheating, we can lower the printing temperature or increase cooling fan rate to solve.
For the problem of bed adhension,we can look at
bedadhension
for more information.