I wonder if being in the office is just simply more enjoyable for those with power and influence, while individual contributors (trying to get their work done) find they like it more at home?
Alternate take 1: If IC positions attract strongly introverted people, ICs as a cohort will naturally be less desirous of returning to the office than cohorts that require some ability to extrovert (such as management).
Alternate take 2: ICs are responsible for their tasks/goals. Managers are responsible for the tasks/goals of their managed individuals as well as the health of the team. People aren't machines. Managing people is not as simple as checking if they're completing sprints on time. Are they overworked? Underworked? Happy? Depressed? Engaged? Disinterested? These sorts of assessments are important yet can be hard to determine remotely.
If managing requires some amount of extroversion, and also the ability to not just measure that boxes have been checked but attest that boxes will continue to be checked in the future, it follows that managers likely are "more keen for a return to the office".