My friend has an issue with her iPhone. For some reason, the phone app suddenly started to show the wrong caller name. After this she tried to logout/login into iCloud and then all callers in the call journal displayed as "00000000". In the Contacts app she can see the correct names with matching phone numbers. Sometimes, the call can have the name of one contact but photo of another one. Contacts are also sometimes shuffled for outgoing calls. Same problem with iMessage.
This is not a new phone, there have been no restores from backup recently, also there have been no new iOS devices connected to this Apple ID recently. She has been using the same phone company for a long time (Vodafone).
And these 00000000000 calls are not spam, it's a real people.
The phone was updated iOS 12.4.1 when she got this issue and it didn't help - she still had broken contacts.
Any ideas how to fix it?