Likely for targeted users only.
Maybe check your inbox if you have a Plex account and have subscribed to their newsletters.
Email quote:
Lifetime Plex Pass only $74.99*
As a way of saying thanks for sticking with Plex over the years, we’re extending a throwback offer on a Lifetime Plex Pass for our loyal customers—that’s you!
This exclusive deal is unique to you—please don’t tweet or post about it—and is only valid now through 11:59 PM UTC on Thursday, March 4, 2021.
Wouldn't it be easier to just have a permanent sticky at the top of ozbargain saying "check your emails for targeted promotions"?
Plex send these out very often to random people using a secret formula nobody really understands. Most people won't receive this promotion.