Gen z and sex?

Where has this idea that gen z is having less sex come from? My last job was in retail, which was 90% gen z women and most of those girls had multiple guys they were sleeping with. I haven't personally seen anything that makes me believe gen z has more or less sex than my generation( millennial). What i HAVE seen is: 1. How far they go to keep these relationships secret and i don't mean hiding the fact that they're having sex with someone because that's nobody's business. I mean straight up pretending they don't know someone in public while sleeping with them consistently. 2. They have sex sooner upon meeting a partner, not talking about a gf/bf. 3. Even though they don't mind secret flings and juggling partners their social media feed is mostly about finding a long term partner who makes it obvious they want them and isn't nonchalant about them. 4. A LOT of gen z girls are trying to get guys my age but honestly I don't know if it was the same when i was their age. Are gen z guys also going for older?
I'm not trying to talk s**t this is just something I, as a people watcher, have observed and wondered about.