Old number & WhatsApp username reappear in iCloud

I create an new empty account on my icloud. It is synced to my local phone and as I tab on it in the contact app to look into the details, somehow an old phone number and a Whatsapp username are added. Trying to delete those data does not work because that data disappears as soon as I access the "modify contact" mode.

What brought me to this effect?

• Person A is existing with a phone number 11 (also Whatsapp number) on my phone.
• Person A sends me another mobile phone number 22 of Person B.
• Via my contacts app I saved the new number 22 under Person B. This is also a valid Whatsapp number.
• Person A then told me later that the new number 22 is also on of hers and sends me real number 33 of B.
• I copied the 22 number to Person A
• I deleted the 22 number at Person B
• I added the 33 number to Person B (33 is not a valid Whatsapp number)
• Result was that as soon as I search Person B in my contact list of IOS contact app, it shows now numbers 22 and 33. When I tab on modify contact, the available menus only show number 33. 22 is gone.
• I deleted Person B.
• I added Person B in iCloud again as described above and faced the issue I described above.

It seems that I always get the 22 number showed as soon as I create a new contact "Person B". When I change the name slightly, it works but that is not what I want.

Remediation steps I already took:

• Exclusion of contacts and whatsapp of "search" of IOS
• Deactivation of whats app having access to contacts
• deleting contacts app and reinstalling it
• restart phone
• turn off icloud sync of contacts app and delete the contacts on iphone. Enable sync and get iCloud contacts synced.

Can someone help me resolve the issue?