I have a google home hub, and a google home mini. Both have the same issue.
Just before Christmas, our young dog (8 months) had a radical behavior change. Previously, she was a very active and playful puppy. But on Christmas eve, she started hiding under a blanket constantly. She would not play with toys. She would not eat in the kitchen. She would not even come out to go pee or poo. She acted very afraid.
After a week and $500 of vet bills, there is nothing physical wrong with the dog. No physical cause. But the vet asked if we have Alexa or Google home, and said that high frequency sounds emitted by those devices can be a problem.
It looks like an update was pushed by Google, just before Christmas, and turned on Ultrasound Sensing on both devices. This is a SERIOUS PROBLEM.
My vet recommended turning the devices off and throwing them in the trash.
I would prefer that Google just refrain from turning Ultrasound Sensing on, when my settings say it should be off.
If it gets turned on again, I will follow the vets advice.
Google Nest's help page says ultrasound sensing is on by default (under Settings | Recognition & sharing). It's on for all of our devices, but I don't think I've ever checked before. Fortunately, our dog doesn't seem to notice.