Screen changes to maximum brightness with no action on my part

My Apple Watch 3 has a problem with the screen brightness which seems to have occurred since I bought it just over a year ago

• With no action from me the screen goes to maximum brightness
• This is despite the brightness setting being turned down. In order to reduce the brightness I have to turn it up first & then down
• This seems to occur irrespective of ambient light or conditions
• The watch software is fully up to date
• I have deleted the watch from my phone & re-paired as per Apple Support suggestions more times than I can remember, this works for a while
• I have reset the watch several times, again this seems to work for a while