On the page linked, there is no documentation about the blue frames that appear in the MicroProfiler when there is a Render bottleneck.
I was only able to figure out the frames are blue because of Developer Relations who informed me that the frame signifies a bottleneck where the Render time exceeds the Jobs time.
Image of the blue frames mixed in with the regular orange frames:
Thanks! For anyone else viewing this, the blue bar description is under the Using The MicroProfiler section. Unfortunately they didn’t provide an image of the blue bars and there’s only a text description.