You actually might be better off on the Pay as You Go plan, but it depends on the details. For truly tiny deployments, the rough preference hierarchy is: Legacy Hobby Plan > Pay as You Go > early-2024 Hobby Plan.
Basically, the first one wasn’t viable (for continued enrollments) for Fly as a company, and the last wasn’t that popular with customers.
@khuezy’s first sentence about the $5 waiver is unfortunately true, but you still might end up paying less. (Just not zero.)
(I doubt the speculative part, though; I’ve never worked with VCs myself, but Private Equity types, their close cousins, are remarkably non-detailed. The odds that one of them said, "My Chicago minions, you may keep the demonic goat with ‘SOC2’ branded on its hindquarters, if you must, but start consuming credits immediately," are close to nil…)
If you have the early-2024 Hobby Plan then the $5 is probably just the fee for the plan itself—independent of actual resource usage. The $0 might be the amount remaining after deducting from credits.
The most recent invoice should show a breakdown of various charges, or you could look on the Billing part of the dashboard under Preview Invoice to see how the current month is shaping up…