There have been lots of posts about this gaffe.
I’m concerned that we’re fixating on little things (which, yes, add up to big) which are unpersuasive to voters at large. Better to attack things like his promise to cure major diseases (as though it simply wasn’t a chosen priority for the last N presidents) and other utopian plans.
A lot of things that happen in American politics are unfair. Whether it’s fair or not a lot of Americans have the idea that Biden is losing his marbles. That’s a real effect.