I really would try and speak to her directly and just ask her if there is something wrong as you are finding her behaviour to be unprofessional. If you can’t bring yourself to do that then I would probably escalate it but make sure you have a good list of examples x
A thing I do when people at work are rude to me or short etc. I ask them if they are ok in a very concerned manner. Majority of time they stop doing it (eventually) If this doesn’t work then yes, address it with her in a friendly manner. I would just say I observed so and so and that she seems to be unhappy and that I would very much like to know what has happened and what is needed for us to have a good relationship. Open the convo I feel you on the work side. Just FYI there’s still places where you can wfh for a couple of days or more. I work for a corporation and still get 2-3 days at home every week (sometimes more)
I would escalate it. But part of being able to stand up for yourself is to be able to brush off people who don't matter, and setting boundaries about her ranting. I'd tell her I don't want her to rant to me anymore about other people, and let her know nicely when she's being rude. It can be so difficult, but use the distance between you to your advantage.