Subsidies for the animal agriculture industry are still lopsided against veganism, and the Far Right escalation in social media awarded by algorithms favors carnism over veganism.
I like to think that veganism is more of a grass roots (pun intended) movement focused on whole foods in favor of processed foods.
All these things may contribute to veganism's seeming decline in the last few years, although I may be wrong (and that decline may just be a lack of reporting)