IIRC they had recently added a user cap on self-serve customers which was new and led to this. The new pricing deck they sent was "It will be $3,500/mo, but until the end of the month, you can get it for only $2,500!" (Pricing approx.)
But it's not to host a static site, it's one click CD, multiple environments, global CDN, and a few more things. I'm not going to say how mu h it is worth, but if you just want a static site with a domain you can do it for free/sub $10 on many many providers.
Sounds like the OP didn't ask for or want those things. I think it's reasonable to be annoyed that a cheap tier that provides exactly what you want and nothing more has been taken away.
SSO is probably the only thing. Other than that, no idea. Netlify pulled the same stunt with us and we left. They must have burned many bridges by now.
That's not a fair comparison. Looki at Netlify[0] and Vercel's [1] pricing sites, the per-user pricing for the "pro" tiers is the same and Vercel gates the features that are in the Netlify "business" tier behind an enterprise contact-us paywall.
I suspect that if you're using these "as expected", your bill on both sites would be the same.
$2,500/mo to host a static site is ludicrous.