What happens these days when you reach Jira Cloud limits?

[Matt Doar _Adaptavist_]

I'm putting together a talk about "The Limits of Jira Cloud" and am not finding clear documentation about what happens when you reach limits with it.

1. I expect the pop-up warnings and alerts to be the main way of telling admins that there is a problem, but do site admins also get emails?

2. If you do exceed the user count, does Jira prevent you creating new issues? This is what I'd expect

Extra thanks for pointers to any docs, but subjective experience is very welcome!