Yes, same phenomenon here (and a few more mentions in the AppleWatch subreddit).
Not sure if it's just strange timing, or if it is to the iOS 15.3 and WatchOS 8.4 update that happened Wednesday, that seems to be the time the Wallet stopped syncing.
Interestingly, the sync does work from Watch to Phone, if you remove a coupon/ticket on your watch it will be removed on your phone as well. No operations on the phone does sync to the watch though, neither added or removed tickets.
I tried chat support with Apple yesterday, but they were at that point unaware of the issues. The agent simply emailed me links to the support guide on how to add/remove items to the Wallet.