I assume this is a cellular model (red ring on crown)
Does your correct number show when you call a friend?
Make sure that in iPhone, Watch app, My Watch tab, Notifications, Phone, are set to Custom, Allow, with Sounds, Haptics both on.
If that does not help, I would unpair the Watch including removing the eSIM then pair up again.
Unpair and erase your Apple Watch – Apple Support (UK)
(this will create a backup too)
Then set up your new watch
Set up your Apple Watch – Apple Support (UK)
which includes this article how to set up cellular
Set up cellular on Apple Watch - Apple Support
or in UK
Set up mobile on Apple Watch – Apple Support (UK) - takes about 20 minutes
If still no good contact your eSIM provider.,