Redirect from cutome domain to firebase domain

Hello there,
I am looking to redirect from my custome domain https://mydomain.com/__/auth/action?mode=resetPassword&oobCode=kUeTmBlryHUBdRHQie6UtHytGwxaUmUc97IZvu31pMYAAAGO8cwpbA&apiKey=AIzaSyA3qvYznndCj01hcI9AoRcmioPSytziK-w&lang=en
to
https://appx.firebaseapp.com/__/auth/action?mode=resetPassword&oobCode=5BHDMJR9jTSVyAfoDHFro10jjKDXM8OKgcLaWNIOj4gAAAGO8fESgA&apiKey=AIzaSyA3qvYznndCj01hcI9AoRcmioPSytziK-w&lang=en

So, I just want to change the hostname form the URL and keep the reset of it same.
I tried the Page Rule:
1- I put URL as this : https://mydomain.com/__/auth/*
2- Pick a Setting as: Forwarding URL
3- Enter destination URL as: https://appx.firebaseapp.com/__/auth/$1
But the rule never triggred, and the request went to my website.

Ensure the DNS record for your domain is proxied and not set to “DNS only”.

Thank you @sjr, for the advice. But it just works when the url like this
www.mydomain.com/__/auth/action*
not for this
https://mydomain.com/__/auth/action
or this
https://www.mydomain.com/__/auth/action

So, I tryied to use this patter in the URL section:
mydomain.com/__/auth/
but didn’t help

thank you @sjr, that helps.
But the issue is it just works when the link start with www.
not othere things like https:// or https://www.

I tried use this pattern but didn’t helps
mydomain com/__/auth/” but didn’t help --“Without spaces”–

I can’t see your URLs anymore, but from memory it was a Page rule.

If www is the only subdomain you use, you can change from https://example.com/* to *example.com/* and $1 to $2.

or if you have other subdomains, then create 2 Page Rules, one for example.com and one for www.example.com.

Thanks, I tried that but still just www.* is working

It’s hard to test with the obfuscation in the screenshot and not knowing the real domain. Can you share these?

Also, I tryied this

I am sorry, I just hiding domain name some thing like this
mydomain.com and app_name.firebase.com