Hello lefkothea68,
It seems a common symptom between the apps being mentioned is that they are not able to send and receive properly.
We suggest you restart the watch and the iPhone it is paired with.
Power cycle the iPhone by pressing and holding either volume button and the side button until the power-off slider appears. Drag the slider and wait 30 seconds for the device to turn off. While simple, this can refresh the iOS, apps and connections. More information is available here: Restart your iPhone - Apple Support
Restart the Apple Watch by pressing and holding the side button until the Power Off slider appears. Drag the slider to the right. After the watch powers off, press and hold the side button again until the Apple logo appears. Be sure the Apple Watch is not charging as it is not able to be restarted while charging.
As for FaceTime, you are able to make FaceTime Audio calls on an Apple Watch Series 7. The different ways to make calls from an Apple Watch are available here: Make phone calls on Apple Watch - Apple Support
Have a good day.