Automisation - Mail & Feedback

Yes, the easiest way to handle alerts is to use dashboard tiles. You'd create a card visual in your report with the measure/filter you want to alert on (in your case revenue decrease amount over some time period), pin it to a dashboard, then go to the dashboard and set the alert there. You don't have to use the dashboard as a visual thing people look at, this is just to get the alert to trigger. 

Alternately, you can use "query a Power BI dataset" in Power Automate to do the same thing - this is more configurable, you can set the email to look and include exactly what you want, etc. You would run this one on a schedule and have it run the query on some cadence and have an if-condition step that checks the query result to see if it's greater than a value before sending the email.

The trick with using Power Automate for alerts is you need to record somewhere as part of the flow when it sends the email, and then use that as part of the notification logic so that you don't spam people (e.g. you need it to run every day to check the value, but you may not want it triggering every day while the condition is true). I did a tutorial on using this action here - the use case isn't the same, but it gives you an idea how to do the query/email actions: https://youtu.be/5-0KH0IiDjU?si=dQCCckYkAV6IbvNa