Im curious about your “ first tore my meniscus” in that I tore mine 5 years ago , had an op , rehab and back running. I was talking to a friend who’s currently out with a suspected meniscus tear , I told him my experiences re the op , but also said my physio had treated young football players who hadn’t needed an op . So question : did you have an op or manage to rehab without one? - really am asking for a friend ?
i ran a lot in my 20s, in my 30s i ran intermittently. I was traveling and using a hotel treadmill and "tweaked" my knee. It was sore and i had an issue walking down stairs at work, but ignored the warning signs. it eventually got better but I would have some soreness or weakness when running soccer practice with the kids. years later when i was seriously trying to get back into training I had a lot of trouble with my knee and at one point serious swelling. went to my GP who thought I had bursitis, but eventually got an MRI with an ortho and the meniscus was torn and part of it was in the back part of the knee (which is why i think this is what happened originally, years ago; also, i had no "event" that I remember, although meniscus can tear just by running with weak muscle support). the ortho sorted out my meniscus and told me he expects arthritis to develop and me to need partial knee replacement in a few years. it doesn't hurt much any more, but i also don't run much any more (too out of shape and overweight to enjoy it at the moment!)
TLDR; definitely your friend should get it checked out now; clean up repair is better than clean up removal IMO.