I’m having the exact same issue with my production environment.
I’m using two different tenants for dev and production, but the app settings in Auth0 are the same in both.
Dev works, production doesn’t.
I also tried using older code that used to work with current setup and it doesn’t anymore.
So I’m risking a guess it’s not on my side. Did an update go live over the weekend or something?
There has been an update to Universal Login on the 14th according to the changelog.
auth0-js ver. 9.12.2
But as I mentioned before - the same code works on one tenant but not on another with the same settings.