The same is true for Micronaught or Quarkus. Learn the frameworks. But they are not a new open standard.
People don't really talk about Jakarta EE as "the standard". Haven't been doing that for quite some time.
You learn it so you don't hand Spring the ultimate monopoly. I thought we all didn't like monopolies? Why give Broadcom one?
Newer frameworks like Quarkus are specifically built for container usage and applications built with it are a bit faster and smaller than Spring boot.
It looks like the industry is moving away from architectures like EE. The desire now is more like a Go deployment: single, self contained deployable. There are make frameworks that support this goal. Maybe EE is one of them, but it's not essential like it was in the early 2000s.
EE doesn't exclude that model at all.
For the most part, maybe like 99%, the Jakarta APIs are agnostic of what the deployment model is. They are APIs to validate input, service HTTP requests, store data in databases, look up roles, connect to identity providers, etc etc.