Actually, it was obvious in 2020. I want to write about how rigged US politics happens to be, but Biden "beating" Sanders in the 2020 Democratic primary was a case in point. The "Hidin' Biden" thing came from the liberal media because Biden wasn't doing interviews with even friendly pundits.
Sorry, right wing media, but the Democrats are in no way a party of the "left". They went with Hillary Clinton in 2016 and Biden in 2020. They would rather lose with candidates like these than run someone like Bernie Sanders.
And Sanders is pretty moderate if one leaves the US.