I think there might be two different parts to this question: are younger people into medfet at the same rate as older people (presumably when those older people were of the same age), and of the young people who are into medfet, where are they connecting.
As far as the first one goes, my guess would be yes? Sure medical practices are changing, but medfet was always niche and from reading here there are lots of pathways into it. Aella on twitter did a survey of fetishes/kinks a while ago, and if I'm remembering right, doctor/medical was listed as something that was significant, but not ultra-common.
As far as the second question goes, my guess would be twitter or other social media, maybe fetlife?
Two more points: when I joined this site, I was in the "20s-30 max" category, now I'm not. Age of people signing up is an empirical thing. It would be really interesting to see an age breakdown of people's profiles here, and compare it to other data, if it exists.
On the other hand, there have been a bunch of stories recently about how young people are having less sex, and fewer relationships across the board. Presumably less sex means less kinky sex too, which would negatively impact how many people are into medfet.