Custom params not passing into authorize URL

I am passing to the /authorize endpoint the display and login_hint params.

https://DOMAIN/authorize?audience=DOMAIN%2Fapi%2Fv2%2F&scope=openid%20email%20address&display=signup&login_hint=john%40gmail.com&client_id=CLIENTID&response_type=code&redirect_uri=REDIRECT&state=STATE

However, when this page is rendered, the display and login_hint are stripped from the url.

All the documentation I’ve read indicates that these params should be accessible in the URL so that I can use the config.extraParams to use the value.

Even the Universal Login has specific code that is looking for the login_hint.

var loginHint = config.extraParams.login_hint;

What am I missing here?

I’ve seen other people propose using params in the redirect URL, but that was discouraged since you may not allow params in the redirect URLs.

But now I’m thinking I could do a different approach. I could customize the redirect URL depending if the user is on a login or sign-up experience, and then just use the redirect URL to determine what to display on the Universal Login page.

If I really need to key this off the redirect URL, then I’ll come up with a redirect for signup success and login success, but that seems unnecessary when according to your own documentation and code, I should be able to at least pass the login_hint.

So while I think I have a workaround, I’m trying to understand how Auth0 expects me to do this. It seems like there should be a more elegant solution than what I’m about to move forward with.