There is an update to the story about the Nintendo Switch firmware update 19.0.0.
There are reports going around that the firmware update may be causing some issues with the GameCube Controller Adapter, where the device simply won’t function until the Switch is restarted. While it is unknown how widespread this issue is, one thing we do know is that those experiencing it are using the official GameCube Controller Adapter from Nintendo and not a third party adapter.
That is not all though, as over on Reddit, some Switch users are complaining of their system not going into sleep mode properly, remaining warm, and also seeing battery drainage happen more quickly when played handheld. This is apparently happening to all Switch models, so it remains to be seen what Nintendo will say on the matter.