@Nico_Lam, hi, you can try this way:
enter settings
select general
select about
slide down until you see data privacy at the end
long press the lower button to enter the service interface
slide down and select “Select OTA pkg”
Now, you can see the current firmware version and the previous one, so select the previous version to downgrade the watch.
The only concern is that if you have installed the latest (glorious) firmware 2.50.28 starting from the second to last (equally glorious) firmware 2.50.26, probably, at the end of the above procedure you will see, as previous version, the 2.50.26 one… Good luck!
