Usage of ${__user.id} in alert message box in grafana version 8.5

I need to send the user id of the user in the alert message from grafana to slack. hence i am using ${__user.id} in alert message box. but i am getting ${__user.id} as plain text in slack and not the dynamic id.

Alert doesn’t have user identity, so it doesn’t make sense.

can I send value any variables from in grafana alert message Global variables | Grafana documentation ?

See linked doc:

These variables are useful in queries, dashboard links, panel links, and data links.

It doesn’t mention alerts. But you can still try it. If it is not working, then you can assume, that those variables can’t be used in alerts.

Noted. I got your point.
Can you please check Fetch alert timestamp