For what it's worth they're not trying to hide this change at all and are very upfront about it and made it quite simple to opt out.
They do not make it very simple to opt out. That is false.
On Android for instance I invite you to use the GitHub app and modify your opt-in or opt outside settings... You will find that nothing works on the settings page once you actually find the settings page after digging through a couple of layers and scrolling about 2 ft.
They didn't even link the setting in their email. They didn't even name it specifically, just vaguely gestured toward it. Dark patterns, but that's Microslop for ya