Hello, i had the exact same problem, tried everything even a clean restore and erase all content and data but nothing worked. I then copied all data from my wife’s iPhone 13 pro to my phone because her phone did not have the glitch. To my surprise the glitch was gone after her data on my phone. Then again i rest all content and settings and the glitch came back. So what worked for me was that i copied my few months old iPhone 12 pro max data from icloud, i was sure at the time i did not have the glitch. After that backup my siri suggestions are working perfectly fine without any glitch. The technique of pop down type random and lock iPhone has been checked many times as well. The problem is gone 100%. Just make sure you restore from old icloud backup when you were sure the problem was not there.