It also carries a more subtle connotation where a sunset is relatively peaceful, in contrast with a more violent and/or forceful verb like "terminating", and could also be seen as more inevitable.

The usual meaning is that it's a somewhat gradual discontinuation, but in this case I think it's an attempt to be polite towards those who made the decision to use React Native in the first place and to the creators of React Native.

Scrapping it, ditching it, dumping it, etc, sounds too much like React Native is crap and someone made a mistake choosing it.

"Sunsetting" is a very common term (in America, at least) for deprecating or discontinuing something.

'gradual removal in stages' -- it is common in the United States for lawyers, government administrators, human resources managers, and others who make changes to important legal policies describing use and restriction of goods, services and repetitive payments, to describe this way.. (the phrase also has a mind-dulling, sleepy effect on the victims as a desired side-effect..)

It's just a euphemism to make something sound nicer. Also see "pivot", "readjust" or "awesome journey".

The original meaning is more like "slow phase out" or similar but now nothing gets "cancelled anymore". Everything gets "sunsetted" so the original meaning is lost.