Gitlab Applications Redirect URI not a valid URI

Hi :

• On gitlab.com
• I created an OAuth application, named drone.pegasusio.io, with redirect URI http://drone.pegasusio.io/login
• I bought the pegasusio.io domain name, and added a CNAME record for drone.pegasusio.io
• I also could ssuccessfully acces in browser http://drone.pegasusio.io/logout and http://drone.pegasusio.io/login of course sends me to Gitlab to authenticate using client Id and Client Secret.
• I can't fathom why, But when I open http://drone.pegasusio.io/login in firefox, after redirection to gitlab, I have an error message The redirect URI included is not valid.
• note also : http://drone.pegasusio.io is on my private infra on AWS, and I am trying to integrate gitlab.com and drone as delegate CICD
• Also note that my setup is : drone deployed in kubernetes cluster inside my homelab, with inlets operator that exposes my drone server at http://drone.pegasusio.io (public domain, you could try yourself, if I did not shut down my home machines in a few minutes)

Additional data

Here is the URL that I have in address bar of browser, when the gitlab error message appears :

https://gitlab.com/oauth/authorize?client_id=668bc88517e21ccabc10499f248466fec02e7781e17b62b63e25e1fafcbf0982&redirect_uri=http%3A%2F%2Fdrone.pegassusio.io%2Flogin&response_type=code&state=9b6cffa2ba517936