I'd like to make a note that these tests do not cover feature differences within the Safari ecosystem since this is only comparing Safari macOS (the only OS tha

I'd like to make a note that these tests do not cover feature differences within the Safari ecosystem since this is only comparing Safari macOS (the only OS that allows other browser engines). Safari on iPadOS has fewer features available than Safari on macOS, iOS even less. Missing features between Safari for each OS are either because they default to off (but the user can enable them) or they are explicitly not available. For instance iPadOS supports MSE (Media Source Extensions) but iOS does not, despite them running on the same SoC. I do not recall having encountered such differences with other engines between different desktop/mobile operating systems. Since Safari on iOS has the greatest number of users of all the Safari versions it should be used for comparison, and not Safari macOS.