Name one application which uses HATEOAS.

I have built a few. And of course there’s a lot of interest in the community around various HATEOAS specs. People build with HAL, Siren, JSON:LD etc.

Any server rendered HTML site or application?

Never used it on ASP.NET or Java EE/Jakarta EE/Spring.

Were you exclusively building SPAs with all of those frameworks? If you ever rendered state/content to HTML on the server you were using HATEOAS (and REST) principles.