You are right , the same problem can be solved with this method , Thank you ijose83 !

You can do a timemachine backup , and downgrade to 12.0.1 , recovery the timemachine , dragging the mac hd then delete , 100% work for you .

Have you tried adding a hard drive to Spot Light? And then to remove the hard drive againt.

Running 12.0.1 on my MBP 14 and iMac 2020, I can search in Outlook normally