For what it's worth, the coverage I was watching was hosted by two Latinx people and they were saying the same thing, but specifically about Cubans in Florida (I don't think they mentioned Venezuelans, but I might just have missed it).
So, at least from that POV, it's not "Latinx cost Biden the election", it's "Cubans (and Venezuelans) in Florida voted for Trump". There was also some discussion that this isn't the case for Latinx voters elsewhere in the States, but also that - surprise, surprise - the Democrats have taken the Latinx vote for granted and that may be working against them now.