[Firebase Founder here] I’m very sorry for the surprise and frustration experienced by the poster, especially due to problems working with Firebase support. We’re embarrassed by the level of communication on our side, and we’re working directly with this developer to resolve the issue.

There are a couple of things I’d like to clarify, to help folks understand what happened here, and hopefully help others avoid the same problem.

1 — The Firebase Realtime Database charges for SSL overhead on all requests (we charge for all OSI Layer 5 network usage). We’ve always had a policy of charging this way. Unfortunately, we introduced a bug late last year that began undercharging for SSL, so when the bug was fixed it surprised many people who had gotten used to the lower numbers. For most people, the change was very small. For a small number of people though with exceptional use cases (ie. tons of small network requests from IoT devices without support for session tickets), this can result in a larger change. We identified and contacted developers who were significantly affected, but this customer didn’t get the email. We should have done better. (we mention this change in our FAQ — https://firebase.google.com/support/faq/ — under “Why was my Realtime Database reported bandwidth lower than average”)

2 — We recently started actually enforcing overages on legacy plans and our current fixed-price ($25/mo Flame) plan. This is a new — in the past, we allowed unlimited usage on every plan, since we hadn’t built the tools to control this. This meant that many of our developers were getting far more than the listed limits for free. So you may start receiving emails now warning you of bandwidth overages, not because your usage patterns changed, but because we’re now enforcing limits for your existing usage. If you upgrade to the Blaze plan, you’ll start being billed for your full usage amounts — so double-check your database’s “Usage” tab before upgrading.

I’ll be looking into our profiling tool to see if we can improve it to give a more complete picture of costs.

Again — I want to apologize to the poster for the poor support experience. If others on the thread have had similar problems and feel they are not getting the attention they want from support, feel free to email me directly as well: andrew@firebase.com