Centrists haven't changed. The Liberal perception of them has changed. Largely because the right has gone so far fascist that it's pretty difficult to defend allowing them into office, even if you don't agree with the left on an issue or two.
The "centrists" that I know stand on the same ground they stood on 20 years ago. If we're talking about the ideologies then I feel that the right has moved further right, and the left further left, which would leave the centrists about smack dab in the same spot. If we're referring to actual political parties then the left has moved further right too. Biden is not a leftist. Any actual leftists get clobbered by the DNC.