Unless there is a sharp edge on the saddle under the G string, you might try changing brands of strings. Someone mentioned Elixers, and they were known to have a problem a few years ago with breaking strings, and that problem may have recurred.

But I would carefully check for any roughness or sharpness under that string. The side where the strings exit the pin-holes should be butter-smooth. Someone mentioned putting the saddle in backwards, which would put the sharp edge under the string, and any sharpness or roughness is a problem.

It is unlikely that you are suddenly playing differently, different enough to start breaking strings. I assume you didn't used to do this? If not, it isn't your playing, and it has to be something mechanical between the string and the saddle.

Bob