Currently, I’m setting Grafana bigquery alert, my goal is to trigger the alert when current count drops 20% compared to the count at the same time last week. [P.S. We treat every 15 minuates as a point]
I also set variable $country and $platform in bigquery query.
I might be not able to help that much but I will try my best because looking at your provided screenshots looks like an issue which might be better to get reported to our GitHub repo.
However, before doing that, could you please try to reproduce this same issue on https://play.grafana.org/ and then share the dashboard link so that we can view it?
(I see that in play.grafana.com, you can select any existing dashboard panel and just change the datasource to Google Bigquery and put a test data there to reproduce it).