I think younger people have a much broader definition of "mental health". Somebody 50+ might say "mental health, like a mental hospital? no thanks", somebody in Gen Z might say "fr fr i always talk about how stressful school is with my homies".
The older crowd is much less likely to advertise to one another that they have a shrink, whilst Gen Z is gonna jump on their phone after a session and say "yoooo guess what my therapist told me today" to their group text chat, so I'd say GenZ talks a ton more about mental health than older cohorts, not simply that they have a broader definition.