I welcome me and hello to all.
Of course i have the same issue and it was driving me crazy not knowing where it came from. It is my airtag, and yes i have it on my dog!
I haven't realise the drain, i have a new iphone 12 and it lasts a full three days. I have the air tag for a month now and i see the "find my" background activity to be 50% or 60%. Not always. I notice when i run and play with the find my dog, it remains high and keeps climbing. When i force quit the application, the next day is on 10% , the next day on 15% and when i have my phone near my dog the next day is on 30%, if i then open the "find my" it just goes to the roof and the iPhone lasts for two days at most.
The only solution now is to remove the airtag from pairing? Is there a light on the horizon from Apple that they have recognise this as a bug and to hope for a fix soon ?