Make the spinner which appears when leaving a space prettier

### Your use case

#### What would you like to do?
When leaving a space you're a member of, the process can take a while. During that time, there's a container with a spinner displayed:

I'd like us to make that container look a bit prettier.
#### Why would you like to do it?
It's kind of weird seeing a container with a left-aligned spinner and no other content.
#### How would you like to achieve it?
I think we could either center that spinner or add some text like: "Leaving XY space".

### Have you considered any alternatives?

Perhaps we could also remove this whole container and leave only the spinner in the center.

### Additional context

_No response_

### Are you willing to provide a PR?

No