Saw iMac sonoma display once, but now the regular screen display is black.
I recently updated my iMac to Sonoma and it worked great, I could see the pretty new screensaver when switching windows. 4 days after upgrading, I used the Migrate utility to set up my new MacBook from the iMac, and I now see a black screensaver on the iMac, even though I have selected the new screensaver in iMac settings.
iMac 21.5″