Can't get original URL parameters on Okta-hosted sign-in page

Hi,

I had a proof-of-concept a couple of months ago to get the URL parameters (ie. clientid, redirect_uri, codechallenge, etc) using URLSearchParams(window.location.search) in JavaScript on the Okta-hosted sign-in page when it loads and append them to a button that linked to a custom registration app. I could then use those parameters to return to the sign-in page again. It was working fine.
Now however something seems to have changed and when I get the URL parameters when the page loads I only get a fromURI parameter. That doesn’t work if I try to use it to redirect back to the sign-in page.

I’m wondering if something has changed in the last couple of months, and if there is now any way that we are able to get these values?
If not, is there some other way we are able to redirect back to the sign-in page from our custom apps maintaining the state?

I figured it out. I’m not sure why getting the original URL parameters stopped working, but it seems passing fromURI will work if you redirect them back to [domain]/login/login.htm?fromURI=<fromURI code> rather than trying to pass it back to the original authorize URL [domain]/oauth2/v1/authorize?fromURI=<fromURI code>.

Apparently fromURI will only work in Okta Classic though, not if your tenant uses Okta Identity Engine.