iOS 14 update message

it's a bug, report it using the feedback app

you'll have to wait for Apple to fix it

monitor Settings > General > Software Update periodically for the next update

or you an uninstall the beta software How to uninstall iOS beta software - Apple Support

After you install it back.. I believe you need to restart your iPhone and then check Settings > General > Software Update

There is a new build available update to it. And all of the numbers of this beta software have been 14.2.

yes, you would need to re-enroll your device

Go back to the Public Beta site where you signed up and download the app to install it again.

And in the future don't install betas.

Why in the world are you beta testing?

After you have installed the profile go to Settings > General > Software Update.