Repro:

1. Create a new HDRP template project from the Unity Hub using 2021.2.0a14
2. The Baking Shaders progress bar should immediately start on opening the new project
3. From the Lighting Window hit Generate

Observed:
The progress bar in the bottom right of the Editor UI will strobe between the two tasks, which looks pretty broken and is unfortunately quite visible.

Expected:
The two background tasks should be aggregated into one overall batch of work, and the top-level progress bar should show progress against that overall task.

Notes:
Overall task progress to be shown at the top level. Clicking on the progress bar will bring-up the Background Tasks window, and only here we should see the individual tasks when more than one is running.

This is not related to HDRP or SRP, but Async Progress Bar only.