Contacts missing after iOS update on iPhone 16 Pro

Completed an update only to find I am missing some contacts. This is not the first time. IO do not know who is missing util I go to phone them. Friends also report phoning me and I haven't answered no miss call is shown. I have actually stood next to a friend while he rang me and although we could hear it ringing my phone remained silent. This is a massive error an the part of apple

[Re-Titled by Moderator]