Why is the browser version shown in Push not exact?

The Push browser extension collects browser version information from enrolled browsers and reports it in the Push admin console on the details pane for each employee.

Browser profile details - KB 10071
When viewing an employee record, you can check which browser version they're using.

Depending on the granularity of the version information reported by the browser in the user-agent string, the browser version shown in Push may be approximate instead of exact. Browser extensions do not have privileged access to more specific version information.