Just got the tmobile android 12 update on my Oneplus 9pro global version and its causing issues

Hi there, would you be able to elaborate or provide a reliable link for this:

Use the MSM Tool for your device to roll it back.  This isn't an easy process but excellent walk-throughs can be found on the XDA-Developers forums for this.  Once you roll back, which will completely wipe your device, so back it up if you value anything on it.  Enable Developer Options and turn off Automatically Install System Updates.  You will still get the annoying prompt for the update, which you can force close the system update app to get rid of until you reboot your device.  

Also, did the roll back completely resolve the issues you were having?  Right now my biggest issues are:

• the silent / vibrate slider no longer works - the notification that it is working comes up but when the phone rings it is always out loud.
• the direct dial and direct message shortcuts are gone and I am not finding a way to re-create them
• calls disconnect as soon as I answer (sometimes two or three times in a row)
• my WiFi seems super slow