It seems so obvious, I wanted to see more of the timeline, but I could not make that left bar that holds the different groupings any smaller.

I work more in Gantt charts, so the ability to resize and even hide the left panel seemed an obvious expectation. But the Timeline team have not checked notes with the Gantt team, so the products are mismatched in this respect.

Please make it hideable - the whole point of the timeline is to see as much as possible from left to right.