I updated my wife’s and mine iPhones and iPads today with 16.1. Now all 4 devices are experiencing slow to no Wi-Fi connectivity.

After updating your iPad, performing a forced-restart will often clear latent post-update performance issues:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On other iPad models: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.