AttributionTokenInternalError: Error posting to Attribution server

Hey guys,

we implemented [AAAttribution attributionTokenWithError] in 2 apps. https://developer.apple.com/documentation/adservices/aaattribution/3697093-attributiontokenwitherror?language=occ

To track the errors we added logging with Firebase Crashlytics. Based on our Crashlytics logs roughly 8% of the users encounter an AttributionTokenInternalError:

Error:
NoAdNetworkToken - Generating AdNetwork token failed with Code: AttributionTokenInternalError Message: Error Domain=com.apple.ap.adservices.attributionError Code=2 "Error posting to Attribution server" UserInfo={NSLocalizedDescription=Error posting to Attribution server}

Affected iOS versions include:

• 14.4.1

• 14.4.0

• 14.3.0

There are no patterns in affected device models. Seemingly all models are affected, including:

• iPad Pro

• iPad Air 2

• iPhone SE (2nd generation)

• iPhone 12 Pro Max

During our own testing, we could not reproduce any errors with an iPhone 8 on iOS 14.4.1. We were also not able to reproduce any errors with the public beta iOS 14.5.

Are there any solutions to that? What can cause this AttributionTokenInternalError?