The USA issued statements supporting the ousting of Morales. That was the extent of USA's involvement. That does not really make it a "USA backed coup". Unless you believe it just because that's what Morales claimed.
We might strongly suspect it, based only on the fact that CIA has done this in dozens of nations since the episode described in TFA. Or, you know, we could just pay any attention at all to actual journalism [0].
[0] https://thegrayzone.com/2019/11/13/bolivian-coup-plotters-sc...