Not even just the pancakes cluck, the pool one was worse imo, the DIKs in the comments immediately assumed he was banging her, then the walk of shame happened. Most of them probably think MC has already fucked Bella, they just don't suspect the dating part yet.
And Bella is not smart about it either, she could've pretended to catch Derek with his phone in class, but instead, she goes about it as if she knew everything.
If Derek remembers the Halloween party and what he told the mummy, it shouldn't take him long to figure out what's up either.