Last week I tried to watch the "Shut the Fuck Up PSA" from the National Lawyers Guild, and it was age blocked. I did try to log in, but now you have to VERIFY your age too (obviously I clicked off that shit).
But honestly, alternative frontends like Freetube and yt-dlp might not make the cut anymore:
Mpv crashed, and Invidious instances keep saying "video may not be age appropriate"
Edit: My state is soon to perform age verification on social media sites, so this is probably the cause. I'll just have to VPN to other states or countries until VPNs fail/are blocked.
My account turned 18 I think 4 months ago.