Version 20.12.2 on Fedora 33.

In my timeline I have a brown indicator line, on top of the 00:00:00:00. But I cannot find out what it is indicating...

It's about the pre-rendering, this red means that it is not prerender, yellow means it's being processed, and green means it's prerendered

Ah, I see. I think I must have accidentally hit Shift+Return...

Thanks!