Phone numbers disappear from contact list
A lot of phone numbers, that I have had on my phone for years and years, dissappear from my contact list. There is no pattern - some remain, and some disappear. This can be contacts I registered up to 10 years ago, and contacts I registered two weeks ago. Any ideas what this can be, or how to solve it? Some times I find the number again, if I scroll through all sms- messages, but I have to register the name and info again. Other times I do not find a trace at all.
iPhone 7 Plus, iOS 13