I am seeing recurring DCError.invalidKey in my iOS app using App Attest, and I'am trying to determine whether throttling or a quota can be a contributing factor before we look further. Questions Are there rate limits or quotas on generateKey, attestKey, or generateAssertion — scoped per device, per key, or per app? I understand exact thresholds may not be published; what I'd mainly like to know is whether such limits exist and roughly what timing window they apply over. If a limit is hit, which error surfaces? Specifically, can throttling ever present as DCError.invalidKey, or would it always be serverUnavailable (or another distinct code)? Does calling the attestation flow repeatedly in a short window (e.g. several times within a few minutes from an onboarding sequence) risk triggering throttling or anti-abuse rejection? Am I right that generateAssertion is entirely on-device and therefore not subject to any server-side limit — i.e. only attestKey contacts Apple's servers? Is throttling one of the documented causes of invalidKey, or is invalidKey strictly a key-state error (key absent from the Secure Enclave, already attested, from a prior install, etc.)? Being able to rule throttling in or out would help us narrow the investigation considerably. Thanks.