hasn't she already missed like 60+ votes this session? That doesn't sound like she is providing much representation to anyone.
she has shingles and has missed most of march due to that. a disease that has nothing at all to do with mental health and is not directly related to age. my understanding is that shingles is very painful, but not otherwise usually a serious condition.
none of the votes she missed was consequential and i expect that if her vote was needed she would be able to cast it. obviously, if her case is more complicated and she is unable to ever return to the senate floor, that would be a different situation that might require her to take action. but that is not the case or the expectation currently.
incidentally, i believe fetterman and mcconnell have missed more time due to health concerns than feinstein this session.