I mean she literally said she didn’t want to. And that was long before Harris was the nominee.
In fact, she’s been saying it repeatedly since 2012.
https://www.businessinsider.com/what-michelle-obama-has-said-about-running-for-president-list-2024-7 (You can put 12ft.io in front of the https to get around the paywall.)
Now you can claim she’s been lying since 2012, but I don’t think that’s desirable in a candidate, do you?
Cuba cannot catch a break!