Solved: iPhone not holding WiFi
After upgrading to iOS 16.1 and then 16.1.1, my iPhone was not holding my WiFi. I have had this iPhone 12 for years and it held my home WiFi without issues. My home WiFi is the same and has been for many years.
Turn off your 5G by going into Settings > Cellular > Cellular Data Options > Voice & Data, and choosing LTE. This will enable your WiFi to hold your iPhone or iPad.