[ethbr0]

I'd assume those are interface (both user- and code-to-code) complexity at scale.

I.e. 0.0001% of accounts end up in a state (across multiple services) that was never expected, and therefore code to handle it never written, and thus is unable to ever transition because there are circular dependencies

[onphonenow]

For sure. But the path to resolution is weirdly hard at google in these cases.