I am seeing the exact same issue in a 2021 Nissan Leaf SV.
Bluetooth audio works great with the phone. Music played via CarPlay (and the cable) works great.
When the car is stationary, it seems to work very reliably.
HOWEVER, whenever I am driving, almost every single time, there is static using Siri and when I am using the phone.
This phone works great in other cars and I have swapped cables to double check.
I am going to go to the dealer to see what they say. Fortunately, in California, we have a 'lemon law' and as much as I love the Leaf, I am not going to be afraid to create a documentation trail to use it.
In the meantime, we need everyone to complain vigorously to Nissan to get this issue fixed!