I got an error creating a pod with pvc

AttachVolume.Attach failed for volume "pvc-xxx" : googleapi: Error 400: UNSUPPORTED_OPERATION - Maximum persistent disks count should be less than [4]

I have a custom type instance node with 1vCPU / 3G RAM. And truly, this instance already has 4 other PVC attached.

But according to this page, there shouldn't be error

For custom machine types or predefined machine types that have a minimum of 1 vCPU, you can attach up to 128 persistent disks.

What am I missing? What else to check?

I checked GCloud quotas but didn't find such metrics (found only PD size)