The first thing to do is to update your iPhone again. The latest version is now 17.1.1. It resolved several outstanding issues. Then, check your Junk folder. I was missing emails after the updates. They were all in the Junk folder. Once I moved them from Junk to Inbox, email from those senders no longer appeared in Junk. (I did check Junk for a couple days, just to be sure.) The emails properly appeared in the Inbox. Here are instructions:
Move your email messages to a different mailbox
- Go to your Junk folder in Mail.
- Tap Edit in the upper-right corner.
- Select the email messages you wish to move then tap Move.
- Choose a mailbox to move the email messages to the Inbox.
I hope this works for you. If not, this Apple Support link offers some good suggestions if you believe your iPhone is compromised:
If you think your Apple ID has been compromised - Apple Support