The idea that the Bolivian transfer of power was motivated by lithium scarcity doesn't make sense, because there's more than enough lithium outside of Bolivia (or even South America) to prevent them from gaining a stranglehold on the price. Also, you're accusing the Trump administration of having a long-term view of a low-carbon future, which is itself suspect.
What makes a lot more sense is that the US doesn't want China to gain a reliable and possibly even prosperous ally on the South American mainland. While Bolivia will not meaningfully affect the global supply of lithium, the demand for lithium will absolutely affect the economic future of Bolivia, and could even make it a regional power. With the Second Cold War increasingly going global, every square on the chessboard counts.
However, the evidence for US involvement in the overthrow of Morales so far consists of a strongly worded letter from OAS, while the fact that Morales actually lost a referendum asking if he should be allowed to run for a fourth term suggests that there was significant internal opposition to his reelection. But Elon Musk made a tasteless joke on Twitter, so that confirms it.