Makes people feel uncomfortable - that is a lot more common these days.
Asking for documentation in these situations is somewhat routine when the issue is not obvious. Someone who used to be able to work in the office, and now can't return, that's not going to be super obvious necessarily why WfH is needed (and separately a reasonable request).
"An employer may require that the documentation about the disability and the functional limitations come from an appropriate health care or rehabilitation professional. The appropriate professional in any particular situation will depend on the disability and the type of functional limitation it imposes. Appropriate professionals include, but are not limited to, doctors (including psychiatrists), psychologists, nurses, physical therapists, occupational therapists, speech therapists, vocational rehabilitation specialists, and licensed mental health professionals.
In requesting documentation, employers should specify what types of information they are seeking regarding the disability, its functional limitations, and the need for reasonable accommodation. The individual can be asked to sign a limited release allowing the employer to submit a list of specific questions to the health care or vocational professional." - EEOC.