
Best single-source is to 'follow' the promo codes pinned thread here on the forums. someone almost always posts anything new within an hour or so.
Otherwise you have to constantly monitor facebook, and twitter, and discord, and a dozen content creators. It's a stupid but common practice to spread things around a dozen different social media venues to artificially drive up engagement. Stupid because everyone does it, and everyone knows everyone does it, including investors and advertisors who look at engagement numbers damned well aware they've been manipulated.