I know that people like Trump or Georgescu are in a different league in this respect, they lie more and in a more unhinged way, but it's hard to draw a line and say that their votes are don't legitimate becuase their voters were lied to, while probably voters for other parties are putting hope in promises that will be unfulfilled as well.

Okay, I'll get specific now. In the US this typically isn't because the Democrat candidate lied, it's because of obstruction from the right-wing. Sure, Biden promised to cancel student debt, but he was met with obstruction at every step from the right-wing. That isn't a lie from Biden, but the lack of results is what we get when voters believe the right-wing obstructionist liars telling them that student loan forgiveness is evil. So then people call out Biden for somehow "lying" about forgiving student loans, and then don't show up to vote for the Democrat in the next election, because "they are liars".