Why did some of my contacts delete after the update

Hello Kilodeke,

Welcome to Apple Support Communities. It sounds like you're having trouble with contacts being deleted after you updated your iPhone. We are happy to share information that may help.

Are you syncing your contacts using iCloud? If so, do you have Contacts enabled under Settings > your name > iCloud > Contacts? You can find more information here: Set up and use iCloud Contacts.

You may also want to check to see if you are syncing your contacts with any other accounts. You can check under Settings > Contacts > Accounts. You can find a few more details here: If your iCloud Contacts, Calendars, or Reminders won’t sync.

Another place to check is in the Contacts app. Tap on "Groups" in the upper left-hand corner. Make sure that all groups have a check mark beside them.

Take care.