Unable to turn on Safari extensions (iOS 15)

Hi, I’m running iOS 15.3.1 on iPhone 12 Pro. I’ve tried to install a few extensions for Safari but I can’t enable any of them in the settings menu. They are all greyed out (see screenshot).

I've tried uninstalling and reinstalling the extensions and restarting the device but that has not solved the problem.

How can I fix this? Thanks.