Billed Instance Estimate noticeably wrong: shows 2 instances, actually billed for almost 3

[Ryan B]

hi all! i have an app engine project that consistently uses 2 frontend instances, based on cloud console's "Billed Instance Estimate," but has consistently been billed for almost 3 instances, for at least the last few months. screenshots below for august: 1980h / 29 days = ~2.83 instances.

any idea what's going on? is "Billed Instance Estimate" known to be wrong in some cases? i have a dozen or so other apps that generally run on just 1 instance each according to "Billed Instance Estimate," occasionally over, and their actual billed instance hours all match correctly.

thanks in advance!

[Kenworth (Google Cloud Platform)]

Thank you for posting this issue. I recommend submitting an issue report to our billing specialist team that are available 24/7. Please feel free to post any non-sensitive information here once a resolution has been reached.