I reckon Dorries and Johnson had done a deal and that Sunak has thwarted it.
Johnson wanted a safe seat and Dorries was in one. He promised her a seat in the Lords if she resigned and they made a deal. Boris would resign his seat and Dorries hers, and Boris would fight her seat as an Independent.
So duly they both resigned in a coordinated action. Then No.10 released the Resignation Honours List, and Dorries’ name had been expurged, and their plan fell apart.
Now she is recinding her resignation because it is of no advantage anymore.