Another workaround is to give "DiskImageMounter" Full Disk Access in the Privacy & Security System Settings (thanks to HWTech for this tip). I hope Sonoma update will fix this.
/System/Library/CoreServices/DiskImageMounter
- Matti
[Solved] GC 12.0.6 .dmg fails to mount in Sonoma 14.0
Re: GC 12.0.6 .dmg fails to mount in Sonoma 14.0
This was fixed in macOS Sonoma 14.1.