Poor Performance - iOS 18.5 - iPhone 16 pro

Hello community!

I'm wondering if anyone can help troubleshoot this:

iOS 18 has been terrible on my iPhone 16 pro. Each iteration has brought more issues than it solved. I am now on iOS 18.5 and the issues are worse than ever. Please see below:

1. The most obvious and regular problem is the lagging and jerky graphics. Launching apps is not smooth at all. Quite often the app judders open in a staggered fashion. The problem is particularly pronounced when I'm on a FaceTime audio call. When a call is in progress, scrolling in any app is very jerky and not smooth at all. It happens with apple and 3rd party apps alike.
2. Predictive Text: empty fields where there should be predictive text. Quite often I have to type all but the last character of a word before it will suggest anything in the text fields. When it does suggest words, they're rarely related to what I'm typing at all. This used to work great on my previous iPhone 12 with iOS 16/17.
3. Intermittent graphical freezes when opening apps like the camera. The app stays frozen in a half launched state on the screen for a split second before opening fully.
4. This one only began happening since updating to iOS 18.5: When the phone is tethered to my laptop, I get regular 'you are not connected to the internet' messages in Safari. I check my other browsers. Same thing. I check the phone. Personal hotspot is on and the green hotspot icon is displayed on the phone. I do a speedtest on the phone and get great results for upload and download, yet the browsers on my Mac still tell me I'm not connected to the internet. I wait a couple of minutes and the pages then load in the browsers on my Mac.

Apple performed remote diagnostics and couldn't find any problems with the phone, which leaves the software. I'd be very grateful if anyone could offer any insight into why these things might be happening and what, if anything I can do about it.