Ok, I have found a couple of things that don't quite work with Monterey 12.3 ßeta
- LibreOffice 7.3 breaks with Monterey 12.3 ß2 (21E5206e). It crashes randomly after a few minutes. The fix is to upgrade to 12.3 ß3 (21E5212f) or use LibreOffice 7.2 or run 7.3 under 12.2.
- MDS (used to download the latest versions of System Installer) doesn't work in 12.3. At all. Until an upgrade is made the only solution is to use Monterey 12.2 or earlier.