I have got disabled Siri suggestions (general & individual for apps), but everytime on locked screen it appears notoriously (for almost anything: safari, photos, ...). Never got that kind of problems in iOS12. Do you have any working solutions? I've been fighting with that problem for over a year now - it's so frustrating.
Annoying Siri Suggestions [iOS 13.6.1]
Try disabling "Allow Notifications" in Settings->Notifications->Tips.