I can’t commit on how you are doing the search, since I’m not that familiar with using the MLS.
However, I think many of the threads lately have been ignoring the diversity between different areas. I suspect if you do the same search but use La Jolla, 92037 you will find more actives today than last year.
While inventory might be declining in large sections of San Diego, the $1m+ coastal areas, (La Jolla, Old Del Mar, Rancho Sante Fe, etc) seem to have ever increasing inventory.