Apple screwed up the versioning of the Safari 16.3.1 update. Big Sur and Monterey Macs are being presented with a “Safari 16.3” (provided they are running 11.3+ or 12.3+) that is in fact the 16.3.1 update Apple's documentation describes. You can only tell a machine has updated to the proper version by checking the Safari build number
• macOS 11 Big Sur: 16614.4.6.11.6
• macOS 12 Monterey: 17614.4.6.11.6
#MacAdmins