Cheers! Same here.
Got exactly the same issue after the upgrade my G8 Power XT20141-3 to Android 11 . After digging for a while just discovered it is G8 specific. (My wife has a G9 Play and doesn't have this issue. That makes me thing the bug is not mobile operator related)
My finding is this is related to VOLTE only. The bug "self installed" into my G8 Power, right after Vodafone fully upgraded all subscribers to VOLTE. Unfortunately, after the update to Android 11, the VOLTE switch in menu settings disappeared. However, to verify this concept, just need to switch from 4G to 3G network, to kill the VOLTE client and voila - the problem disappears (hence with a mobile data speed downgrade that won't encourage us to leave it with 3G).
In a nutshell, I strongly believe that Moto software team, if they are so kind, would have to issue a patch for this VOLTE client issue, otherwise we have have to live with this bug until next smartphone purchase.
* that is why, bug disappears when calling a landline or any non-VoLTE interconnect of our operators.