I interpreted the question to apply only to pre-requisite course setbacks/challenges imposed by COVID-19. If you feel that a MCAT cancellation uniquely impacted your application in a way that many other applicants did not also experience, I’d recommend calling the Admissions office, explaining your situation and seeing where they feel it would be best to include that information (i.e. secondary, mention in interviews, send letter that gets added to your file if they allow that, etc). This way you can make sure your situation gets fully considered without possibly being penalized by straying too far from what that specific questions seems to be asking.