Sonar Test Sensor shows breath rate?

I have a Google Pixel 4a 5G
Last night, I had sleep as android all night and produced random results
80% deep sleep
no breath rate altogether

When I run Test Sensor it says supported. I can also see wave changing if I move around it and strength is around >1000
I do not see breath rate at all on this screen
Is Test Sensor supposed to show breath rate?