I remember this happened a while back and my theory for the lack of Lexi's B/G scenes mostly stems from her being amongst the top performers now and having more say in what she wants. I wouldn't say she's stopped shooting B/G (at least I hope not lol) but I think she prefers to shoot plot-heavy scenes she can act in rather than gonzo-style scenes. Besides her two appearances for XEmpire and the now rare Brazzers appearance, you typically see her shoot B/G for Adultime, Nubiles, and VR companies.
Though if this were true I would think she would go all in on the VMG brand since they're a pretty plot-driven studio as well.
Given where she's at now and if she does prefer shooting G/G, I also imagine it's now harder for some companies to afford Lexi. I remember she would shoot with LoveHerFilms and Naughty America routinely but it's been 2 and 3 years since she's shot for either of them.