Thanks for your reply. Watch version is OS 7.0.1 & iPhone iOS 14.0.1. The syncing problem started after I did the update.
When I go to the Health app -> Summary -> Steps -> scrolling down to Options -> Data Sources and Access, the apps allowed to read data are the Wellbeing App (from Qantas) & the Data Sources are my Apple Watch, then Health, iPhone, Apple Watch (again). The Apple Watch is at the top so it should read the steps from this source.
When I go to the Health app -> Summary -> Activity -> scrolling down to Options -> Data Sources and Access, the apps allowed to read data are the Wellbeing App (from Qantas) & the Data Sources are Apple Watch on top, then my Apple Watch again, and my Apple Watch again (my Apple Watch is mentioned 3x in the Data Sources, but this might be because I have added data (steps) manually because of the syncing problem).
Funnily enough when I was in touch with Apple Care and they accessed my iPhone remotely, the steps in the Health App all of a sudden moved up to the same amount of steps on my Apple Watch, not having done anything to the device. We thought it just fixed itself miraculously but shortly after, the syncing of the steps was out of whack again.
Thanks