The datasource does not support alerting queries for Expression

Hi! I have a query to mysql database and I am able to use this data for alert, what is great. But then I added a second query and expression and made some calculation and then try use expression for alerting, but got error: “The datasource does not support alerting queries”
Am I doing something wrong? Is it any way to use expression for alerting? Or no matter what I should use just sql query?

welcome to the :grafana: forum, @zerosentoki

Can you confirm: are you using the new Grafana Alerting platform (first released in Grafana 8) or the legacy alerting platform? I should note that the legacy platform is no longer actively developed: