HPA "invalid label value" whent trying to use metrics from k8s-stackdriver

Hi. I am coming here because the issue I posted on the kubernetes repository wasn't answered and a few people seem to have encountered the issue.
=> https://github.com/kubernetes/kubernetes/issues/81976

This link contains all the information needed to understand the issue. I can copy its description here if it is preferred.

Anyway, perhaps, there is a workaround I didn't think about. I lost access to the infra because I changed job since but I can still reproduce I think with the steps I listed.