Where did the playground timeline go?

I noticed in some old videos, including the announcement of Swift, there was a cool feature where you could use a timeline to see the output happen live.

Where did that go? nothing is appearing even when writing exactly the same code as in those old videos. I can only sometimes do the quick preview thing with an unlabelled graph that doesn't tell me anything.

is the playground feature abandoned at this point? Not much seems to work and the templates look like they're from 2015, even the button for playgrounds was removed from the Xcode launch screen
It would have been a really interesting tool for debugging.