Help with flux query

Hi there, really struggling with a flux query right now.

This is the current schema for my measurement:

"measurement": "MyMetric",
 "fields": {
   "value": "number",
   "id": "string"
"tags": {
  "source": "string"

So, I want to either show a visualisation/alert when the mean “value” is different in any month based on “source”, and in that visualisation/alert I want to list all of the “id” fields for each of those months.

I’ve tried what seems like everything, I can’t seem to get this at all. I would post some attempts but I don’t think it’s worth it as this point