Ironically, lately Biden has done nothing to prevent more sections of the wall to be build, approved the deportation of people from Venezuela back to their country of origin,etc.
Biden may be in his golden ages, but as a politician he is not stupid, he knows people from New York (a democrat/blue location, is suffering for the immense inflow of migrants without having a proper preparation and he does not want to be pointed out as responsible for all the chaos, specially as close as we are from the election day.
This all situation is nothing but a softball for the political rethoric of Trump and the Republican party, I would not be surprised his in the following polls Trump started to even take lead over Biden by some points. Because, whether we like it or not, Trump is good enough at using others mistakes against themselves, for his own political benefit..
That's a really good point, yes. Trump's focus in essentially any speech he holds is on the mistakes of his political opponents or on things that he could twist such that they look like a mistake to his followers. He really is a verbal acrobat and I watched him holding a speech just yesterday. Quintessence of the speech was: without him there would not be a single war on the whole planet right now. But all wars there are these days are the result of Biden's political decisions.

But he also often leaves the political arena and pulls as many private issues into it as possible. Ad hominem attacks are one of his major rhetorical devices.