This morning I reset my shield TV back to factory setting via the sheild settings UI. At the time, it was running the latest shield experience. To my horror, this restored old launcher UI (I've grown to really like the modern google TV launcher). I checked to see if there are any shield experience updates. Shield says it was up to date. WTF.
The built in Plex client also reverted back to its old UI (this was resolved by updating Plex)
Back onto getting back the google TV launcher.
I followed the instructions here:
https://www.howtogeek.com/693761/how-to-get-the-google-tv-ui-on-android-tv-devices-right-now/
I ran all the steps up until the ADB commands (ADB not needed for my shield 2017 pro it seems), then I rebooted my shield. Once it rebooted, the new google TV launcher kicked in by default.
I'm hoping Nvidia will resolve this in a future update. Restoring the Google TV launcher on a factory shield reset is less than intuitive.
The old launcher without ads? The horror indeed.