Falling back to file listing mode worked as band-aid, but dont see that as long term solution due to costs related to calling file listing operations (especialy with large number of files).

In practice - i removed the event grid related options from the streamreader:

cloudFiles.useNotifications
cloudFiles.resourceGroup
cloudFiles.subscriptionId
cloudFiles.clientId
cloudFiles.clientSecret
cloudFiles.tenantId

My top candidate would then be the Azure Storage API changes shared by @Malthe