Oh boy...Despite how much cranky old folks and conservatives like to push this narrative, it's just not true.
For those aged 16 to 24 years, the seasonally adjusted employment rate (employment-population ratio) bottomed out at 44.7% in June 2010. By February 2020, it had increased to 52.5%, and as of June 2022, sits at 51.2%. That's still comfortably below where it was in the 80s and 90s, but there are all sorts of reasons why that's the case.
For those aged 25 to 34, as of June 2022, the employment rate sits at 80.2%, jut shy of the pre-COVID rate of 80.6% in February 2020. It's also close-ish to the historical high of 81.7% in June 2000, and way above the 2010 low of 73.5% (and also muuuuuch further above the recorded historical low of 59.0% in February 1950--single earner households, etc.).
That is to say, employment levels for late-teens and early 20-somethings are relatively high compared to recent history, and employment levels of late 20-somethings and early 30-somethings are moving toward historical highs.