Larry Kudlow said that "plant-based beer" phrase in the middle of a diatribe against liberals'/Biden alleged plan to limit beef consumption and supposedly other animal products.
The "plant-based beer" phrase is not commonly heard otherwise and was mocked (on the left) for the fact that beer is mostly plant-based.
Having said that, according to Wikipedia, there is a concern among some vegetarians whether beer contains any traces of animal products:
Some beer brewers add finings to clarify the beer when racking into a barrel. Finings can include plant-derived products, like Irish moss, or animal-derived products, like isinglass and gelatin.
Most breweries do not reveal if they do or do not use animal products in the processing of their beers;
Kudlow may have been alluding to this in an attempt at hyperboles, but since he did not elaborate on the beer angle in the rest of his diatribe, we don't really know if that's somehow what he was referring to by "plant-based beer". According to some of Kudlow's critics, his intent wasn't to be clear about any of it anyway...
Amid a blizzard of lacerating social media send-ups, the New York Times columnist Paul Krugman offered a sober analysis of what Kudlow was up to.
“So this seems to be the latest rightwing attempt to smear Bidenomics,” he wrote on Saturday. “There is, of course, nothing about eliminating meat in Biden’s plans; so this is like the imaginary mobs that burned our cities to the ground.
“If you read what Kudlow actually said, he’s cagey – doesn’t say that Biden proposed this, only that some people say this is what would happen. But Fox viewers won’t notice, which is the intention. [...]
It’s all false claims about evil liberals, which the base is expected to believe because it’s primed to believe in liberal villainy. They’re not even trying to engage on actual issues.”