One of our longtime readers and supporters, Hal Sherman, let us know today that he had received an email from Apple regarding iCloud and the iOS 10.3 update. The email notes that a bug in 10.3 "impacted a small number of iCloud users. This may have inadvertently reenabled some iCloud services that you had previously disabled on your device."
The note, seen above, suggests opening iCloud settings (now found at the top of Settings > iCloud) and making sure that services that had previously been disabled are still set that way. If not, iCloud users can tap the green buttons to disable the services again (see image below).