https://wccftech.com/nintendo-switch-system-update-12-0-0/

Nintendo just rolled out Nintendo Switch System Update 12.0.0 globally but release notes for the firmware update are almost nonexistent.

The update being version 12.0.0 should indicate that this is a major update for Nintendo’s popular hybrid platform, but the release notes only mention that it fixes a save data backup feature. If the patch notes are to be believed, the firmware update doesn’t even add more stability to the Switch – quite uncommon since Nintendo has been making the Switch as stable as a brick house over the past four years (pun intended).