I’m not sure why Garmin didn’t include the complete release notes (below) in the post, but there are tons of changes and improvements since the last stable (8.10) build of the firmware for the fēnix 6. The release is staggered, but you should be able to get it now via Garmin Express.

Changes made from version 8.78 to 9.00:

• Made several stability improvements.
• Fixed an issue with custom alerts.

Changes made from version 8.77 to 8.78:

• Brought in improvements for grit and flow.
• Fixed an issue where the device could crash on the map page during an expedition activity.
• Fixed an issue where the device would crash while powering down if battery saver was enabled.
• Fixed an issue where the device could crash during the multisport activity creation wizard.

Changes made from version 8.76 to 8.77:

• Fixed an issue where heart rate data would intermittently disappear from the HR widget during an activity.
• Fixed an issue with the Stress 4 hour graph.
• Fixed an issue where the training status and training load pages were displaying incorrect data.
• Fixed an issue where the PulseOx widget would not display history data and could crash when exiting the widget.

Changes made from version 8.74 to 8.75:

• Made several improvements to Indoor Climb.
• Updated the UX layouts for smart notifications, heart rate, and solar widgets.
• Made several other bug fixes and code improvements.

Changes made from version 8.73 to 8.74:

• Made several improvements to Indoor Climb.
• Improved the responsiveness of the history widget glance.
• Updated the UX layouts for in activity elevation plot, ABC, compass, temperature, Sunrise/Sunset widgets.
• Made several improvements to the music experience.

Changes made from version 8.10 to 8.73:

• • Fixed an issue where a CIQ watchface would crash if the user were to hit ‘Back’ from the incoming call page.
  • Fixed an issue where selection of an item in music lists (artist/genre) would yield a landing page for a different artist/genre.
  • Added support for downloading workout videos over Express or WiFi.
  • Added support for activities Climb Indoor and Bouldering.
  • Added support for a routes summary page to the activity review flow for Indoor Climb.
  • Added support for the device to manually add a shot through the measure shot page in Golf.
  • Updated the look and feel of the weather app.
  • Updated the look and feel of the End of Activity flow.
  • Improved the UX layout for Altimeter, Barometer, and Notifications widgets.
  • Brought in cross-country ski improvements for Fenix 6 non-Pro models.
  • Made several improvements to the music experience.