I thought betas couldn’t smell pheromones?

In omegaverse all depends on the author likes

In some of them alphas and betas can get pregnant. In some alphas don't bite. In some omegas lose their pheromones after getting bitten. Etc

In most of the ones I've read, pheromones do affect betas, or betas can smell / sense them, but it affects alphas a whole more than betas in most of these stories.

The original omegaverse rules were that betas can’t sense them then it changed to they can barely sense them until it’s literally pouring out of an omega like a heat. Now it’s basically authors choice to do whatever they want under the name.