GitHub no longer uses Toasts

Modals, toasts. The UX set got very good at coming up with new words for pop-ups.

Modals are different from toasts. Modals take over your screen; you go into a separate "mode" for them. Toasts are non-modal; they just take up screen space but you don't have to interact with them.

"Toast" usually implies something that goes away on its own, though that's generally considered bad UX.

It's just jargon. Every field does that. In this case, you can really tell that it's two bits of jargon made up at different times, because one is dry and technical, and the other is a pun on "pop-up".