No sounds on notifications on iPhone when wearing Apple Watch

I’ve lived on silent for a long time so have never noticed this, but the wife has been going nuts for a couple of days because her iPhone stopped makings sounds…

But it seems that this is intended behaviour when you have an Apple Watch (which she does):
https://discussions.apple.com/thread/250193451

Is this true? Has anyone else noticed this?

She does wear her watch alot, but I pretty constantly hear her custom message tone(s)… so either it’s always in her hand (very possible) or unlocked (from being in her hand) or she’s taken the watch off (maybe? But I don’t think so).

Has something changed? Or is this something she has never noticed?

If this is the case and you can’t set custom tones on the Apple Watch… doesn’t that make the custom tones totally pointless for Watch owners?

In her case she was setting custome message tones

I think it’s something you’ve never noticed. I noticed it and questioned it when I got my first Apple Watch in 2015. It’s normal behaviour.

I believe that if the iPhone is on but locked only the watch will make a notification sound. If the phone is unlocked then it will make the notification sound.

I hated it at first but now I understand that having both the watch and phone going off at the same time would be very annoying after awhile.

I think it’s possible to have both make noise but you give up some things, including Apple Pay. Given she doesn’t use that (I don’t know why) it might be something to look into.