lost all notes since 16.3.1 update

Many users who have updated to iOS 16 and above must have a similar issue if the issues stated by you are due to the iOS.

Unless you state what the issue is many in this forum may not be able to respond positively to the issue you are facing. 

With the limited information that you have provided, It is hard to even guess the problems faced by you. 

You may get faster and better responses to your query by --> Writing an effective Apple Support Commun… - Apple ...

Please re-post with detail so that someone else can help.

Please check your email accounts that store all your notes. They are synced to Google, iCloud, AOL, Exchange, Outlook, Yahoo or any other etc.

Where were the Notes that you lost? See the pic below. You will get your answer.

The Aol notes are not stored on the iPhone they are synced to the email account.

Couple of last resort ideas:

Check if the notes are in your Recently Deleted folder: Open the Notes app, and tap on the "Back" arrow in the top-left corner until you see the list of your folders. Scroll down to the bottom and tap on the "Recently Deleted" folder. If your notes are there, you can recover them by selecting them and tapping on "Recover."

I know you mentioned not having iCloud but did you ever do an iTunes Backup via PC or Mac?

If you no longer have access to your old Exchange account, it may not be possible to directly import notes from that account onto your new iPhone. I think the only thing I could suggest is contacting them and seeing if they'll grant you an exception to recover them.