Safari does not render "Merge commit message template" placeholder correctly

In project settings, field "Merge commit message template" does not render the placeholder correctly on Safari.

This is how it looks on Safari:

This is how it was supposed to looks, and looks fine on Chrome/Firefox:

Apparently, the Safari render is the one implementing HTML standard correctly: https://html.spec.whatwg.org/multipage/input.html#the-placeholder-attribute