Incomming call gives always Unknown number

All my incomming calls show “unknow nnumber”. When I don’t answer the call my message box show the person who called if in the contacts list

Is this: a bug, a setup problem or something on the provider site.

My phone is a MI10 lite 5G
Network: KPN/Youfone
I found out when I Turn of “4G for calling” I get phone number and name

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