Might not be auto-suspend. You can switch back to auto-stop and see if this issue persists?
Our multi-region app, which to be fair gets a LOT of traffic (est. 300 to 500 reqs/s), has faced the issue of machines spinning up (apparently needlessly) then never spinning down, for quite a while now: Overriding staged secrets for Machines - #7 by ignoramous
If you’re on the Launch plan (or higher), consider writing to Fly’s support. They’re pretty responsive.