Hat tip: Great follow-up. I asked Google AI about those visa types and it told me:
> F, M, and J visas are all nonimmigrant visas for foreign nationals seeking to study or participate in exchange programs in the United States.
Effective immediately, all individuals applying for an F, M, or J nonimmigrant visa are requested to adjust the privacy settings on all of their social media accounts to ‘public’ to facilitate vetting necessary to establish their identity and admissibility to the United States under U.S. law.
Pick any at random to verify.