If Pop message is giving wrong message then the severity is Low. Because there is no Impact on the Application but Priority is High. Because we have to fix the Issue as early as possible
Malli!!!!!!! Consider a stock banking application, you are selling stocks and at the end your getting pop-up with wrong reference number, instead of reference number application displays a account number still you will mark SEVERITY as LOW.
It's depend upon the situation.
Minor: when any grammar mistake or UI issue.
Critical : If pop-up has OK button but it is not working for close the pop-up.