What is the most current version of Safari?

Current (August 26 2022) Safari version is 15.6.1 (17613.3.9.1.16).

MacBook Pro 13", macOS 10.13

Newer versions of Safari may not be available on older (unsupported) versions operating system.

For macOS High Sierra 10.13.x, Safari 13.x was the last supported version.

Safari 14.x was available on macOS 10.14–macOS 11.

Safari 15.x is available on macOS 10.15–macOS 12.