It looks like the CloudKit silent notification bug was caused by some sort of token validation added in iOS 26.4 that was dropping notifications from CloudKit. Fixed in iOS 26.4.1 by bypassing the validation for notifications that come from CloudKit

Credit to @blacktop's excellent IPSW diffs: https://github.com/blacktop/ipsw-diffs/tree/main/26_4_23E246_vs_26_4_1_23E254#usernotificationscore

@_inside @blacktop Bypassing validation. Seems like a bad plan.
@cronocx @blacktop Probably not a very important validation if they only introduced it in iOS 26.4 😆