I’m a level 1 editor.
That segment seems to occasionally get followed as the actual road, apparently especially for drivers turn from SB Jamboree. But, since the left turn from this segment is marked as prohibited, once Waze thinks they’re on this segment, Waze doesn’t like it when they get back on the main segment.
While I’m at it, the u-turn should be marked as allowed on EB Main at this segment (https://www.waze.com/editor/?lon=-117.83768&lat=33.67996&zoom=8&layers=BFTFFTTTTFTTFTTTTTTTTTFTT&segments=71123370)at Park Plaza.