Hi,
When I receive calls on my iPhone with DUAL SIM a little badge (in my case "P" for private and "B" for business) is shown that tells me which cellular line is called. Until WatchOS 9 this badge was shown on the Apple Watch as well... Since my upgrade on WatchOS 9 (and even with my upgrade to the Series 8) this badge is not shown.
The Apple Watch Guide says the following:
How Apple Watch receives calls when using multiple cellular plans When Apple Watch is connected to your iPhone: You can receive calls from both lines. Your watch shows a badge that tells you which cellular line you received a notification from—H for Home, and W for Work, for example. If you respond to a call, your watch automatically responds from the line that received the call.
I already reset my Apple Watch and set it up as a new watch. I resetted my phone settings as well but nothing changed