Man, I feel your pain, lost three koi to coons my first month too (they even flipped my rocks around like they were looking for something). What finally worked for me was a cheap solar motion light plus stringing fishing line about 8 inches above the water across the pond, since they hate how it feels when they try to lean in and scoop. Haven't lost a fish since March, so skip the fancy gadgets and try the line trick first.

Did you link your autopay to a debit card instead of your actual bank account? That's what got me, I had mine set up on a card that I only use for fun stuff so every bill quietly drained that one while my checking account sat there looking fine. The fix for me was going into each biller's site one by one and switching the payment source, since your bank has no way to know which "bucket" the money should come from, it just sees a charge. Worth checking if you have more autopays on that same card too, I found three others I forgot about.