It isn't in yet. All of the warnings for the full release are included to prevent people from getting attached via the demo only to not be able to play the full game due to the content warnings. So, not every warning exists yet.
The transphobia warning is specifically related to when Violo opens up about how his family treated him, and that scene is further down the line. I can't say exactly when since the game is undergoing a resequencing at the moment, but Violo can mention it in high affection play through when he feels secure enough to be that level of vulnerable.