The conditions are one thing. Though an actual leftist running at the top of the ticket, has down ballot implications. Perhaps better results in senate races, mean we don't have a 50/50 senate.
Beyond that, it's what you do, how you push, what you say, how you say it. Joe hides in his bunker and runs away from certain words, like GASP socialism. Scratch that, he attacks such things and thus voters who believe in them. Voters he wants to vote for him and the party. He has a press secretary who gets into petty squabbles over such things like the idea that people shouldn't have to pay an arm and a leg for COVID testing and masks. He hasn't pushed policy in any meaningful way to the public outside of early COVID stuff. Which has led to journalists and commentators to question his effectiveness and stances, while the public just sees him as inert and not actually doing anything.
There is this constant refrain of, "but his EO will get overturned". Say every single one would. They haven't been so we know that isn't true, but say they were. That would at least be an effort people can see. It would show you where he stands. Not his weak pressers were he sounds as bad as he did on the debate stage with Trump. Maybe it would draw some much needed attention to the Supreme Court. Something the Dems failed to do in 2016.
Finally, what is wrong with people demanding more from their president? I saw the 4 years of Trump. People rightly, asking for conservatives to see reason. To demand more. Joe Biden being a Democrat entitles him to nothing. There is more he could be doing and he's not doing it. Why is it not okay to demand more from your politicians, no matter their party?