Does this “warning letter” refer to the letter received by Trumps son?
I suspect it does, and it leads me to the conclusion that Q is either Trump himself or a member (or members) of his family.
The other option would be an FDA Warning Letter see here: https://www.fda.gov/ICECI/EnforcementActions/WarningLetters/default.htm#recent
However, if it were from the FDA to a Pharma co. it’ll be a few weeks before it gets posted.