I personally took it as he could either still smell dojun on the beta ( which shows he is calling BS that they don't like each other) or that the omegas pheromones changed or got out when he was mad. I don't think dojun entered since it seems like he just found out and he might be a bit far away. Also it would be nice if the beta is an omega since then they can have a baby but I also want him to stay as a beta.
My first thought was that Heesoo was emitting omega like pheromones (but him being recessive too would be a bit much, unless the company perfume has an unknown side affect that really can change your gender because he was using it if I remember right...), I like the idea that CrazyChow started to emit Omega pheromones in anger like Lets Cent said. Honestly not sure, so any guess is possible :)
In that panel with the waft... does that mean he was angry or Dojun entered the building or does it mean that Dojun's lover is an omega this whole time. (Sorry I forgot his name)