According to this:
I managed to actually get the A ending somehow. Copulate if I remember how, but at least that rules out the possibility of the creator procreating something up in the code, as his last login date is way before my message.
Apparently I even posted a comment on the game:
Excellent game. If you're having issues reaching ending A, tell the truth about the plague and have both high fame and popularity.
— Celicni on 1/27/2021 7:44:10 PM with a score of 260
Dunno how the score is calculated but I do seem to have a pretty high one, at least compared to the other commenters. Wonder whether the score is "fame" or "popularity" or a combination of both. Schtup if I know how those 2 dudes got 320 and 370 respectively.
I can only assume people reaching ending B don't have their fame and popularity high enough.