Was the page navigated to using back or forward button?

window.performance.getEntriesByType("navigation")[0].type === "back_forward";

This is how to detect if a page was loaded because the user navigated via back or forward buttons.

Possible values:

back_forward if the navigation happened because of a back or forward navigation
navigate if the navigation happened because of a regular navigation event (like clicking a link).
reload after reloading the page
prerender if the navigation has happened during a prerender hint