gRPC versioned bucket not keeping non-live versions of objects

I am creating a bucket with versioning enabled, adding an object, then deleting the live object and making a GetObject request with the generation number of the non-current object.

Create Bucket request:
parent: "projects/123456789"
bucket {
name: "projects/_/buckets/testversionedbucket"
bucket_id: "testversionedbucket"
location: "US"
storage_class: "STANDARD"
versioning {
enabled: true
}
}
bucket_id: "testversionedbucket"
predefined_acl: "private"

This request correctly returns a bucket with versioning enabled. I then add an object to this bucket and am able to verify that it exists in this bucket.

I then delete the object in the bucket:
Delete Object Request:
bucket: "projects/_/buckets/testversionedbucket"
object: "testobject"

However, when I then send a GetObject request with the generation to get the non-current version of the object, I get this error:
NOT_FOUND: {"error": {"errors": [{"domain": "global", "message": "Could not find object projects/_/buckets/testversionedbucket/testobject/#1660326908572 does not exist."}]}};

This object should exist in the bucket, though since we are using versioning.