The new timeline editor is so buggy, it's constantly refreshing between the old and new format as I edit, and I don't even think I'm using labs for the new feature set.
Among the changes it keeps toggling back and forth, the removal of the scene sidebar seems like an out of touch mistake. I regularly rely on that timeline for easier navigation around my timeline (I'm regularly editing hour long videos) and utilize it often to implement edits across a video that only impact specific scenes. Removing it will actively make my work harder, more time consuming, and would ruin part of the appeal to use Descript's editor in the first place.