Gary Illyes from Google clarified last night that if you place a nofollow in your robots meta tags, it will also follow the new rules as the nofollow link attribute. Hence, as Gary said "Meta robots nofollow is a hint now, like rel-nofollow." Although the robots won't support the new ugc and sponsored attributes.

Gary said this on Twitter:

1. There's no meta robots ugc and sponsored, it won't do anything if you add that.

2. Meta robots nofollow is a hint now, like rel-nofollow.

3. I'll update the docs tonight to say this explicitly.

John Mueller from Google clarified as well saying "The robots meta tag remains the same as before, noindex affects the page, nofollow affects the links on the page. It's just that nofollow on the links is now different. There's no ugc or sponsored for the robots meta tag."

Here are those tweets:

1. There's no meta robots ugc and sponsored, it won't do anything if you add that.

2. Meta robots nofollow is a hint now, like rel-nofollow.

3. I'll update the docs tonight to say this explicitly. — Gary "鯨理" Illyes (@methode) September 12, 2019

The robots meta tag remains the same as before, noindex affects the page, nofollow affects the links on the page. It's just that nofollow on the links is now different. There's no ugc or sponsored for the robots meta tag. — 🍌 John 🍌 (@JohnMu) September 12, 2019

Robots meta nofollow is just nofollow applied on all links of the page as johnmu says somewhere. JM and I are saying the same thing. — Gary "鯨理" Illyes (@methode) September 12, 2019

Here are bit more tidbits on this topic from Gary:

Yes — Gary "鯨理" Illyes (@methode) September 12, 2019

There's no benefit. If you want to help us better understand sites, great! If you don't want to, also great! But either way you won't see a benefit. — Gary "鯨理" Illyes (@methode) September 12, 2019

Ya — Gary "鯨理" Illyes (@methode) September 12, 2019

Forum discussion at Twitter.