There is no evidence of that. Polls compared to themselves show no change. CBS News released today shows a change, but they are required to inform RCP that they made a change to their sampling — and they explicitly say “blacks were oversampled”.
Well that is a 75/25 group. Of course you can move the needle if you sample that group more heavily than you did in your previous poll.
There is no evidence of any changes in attitudes since Biden stepped down.
https://www.270towin.com/2024-presidential-election-polls/
And the poll in this article is 2 weeks old.