The official PixelCommunity Reddit account confirmed that Google has identified the cause of the problem:
Thanks so much for reporting this issue, we’re sorry that you’re experiencing it. After some investigation, we identified the root cause and determined that it impacts a very small number of devices. Of course, we realize this is a poor experience and immediately developed a software fix that will be available in the next Google Pixel Update, rolling out in March.
Affected Pixel 6 series users will therefore only have a week or two to wait until the problem is fixed. Then again, Google’s recent track record with patches means that we’re not confident that a completely different bug won’t arise.
Nevertheless, this latest Pixel 6 series bug was pretty serious as it meant users couldn’t toggle their Wi-Fi on. Affected owners said they tried everything from factory resets and restarting in safe mode to resetting network settings and switching to airplane mode.