Biden should have pulled out a lot sooner. When? At least a year before the election. But you can easily make arguments for earlier and earlier all the way back to having been too old to run for President in the first place, despite having had a really good term.
Also Harris needs to fire her consultants, who were still trying to play "fair" in an unfair fight and pulled back on the one attack line which was working: that Republicans are "weird".
Things are unlikely to improve until voters start primarying out anyone still trying to do bipartisan equivocation.