We are using Azure ADB2C as the auth mechanism in our .Net app. And using MSAL 1.0 to integrate the ADB2C into angular 8 client side app. We understand and doing the customization of the UI screens in the Auth forms using the custom policies and the ContentDefinitions in the custom policies with our own HTML files integrated with the AAD's forms as in the MS documents.
And we have a AD tenant registration as well for clients and in-org associates as well. Within the auth flows for those users, it is showing up the "Trying to sign you in" screen before getting the user into the app & while generating the auth token. An image of it as in this link sample image of the screen
We are reviewing on how to hide this screen or customize the UI/Html here? Observed that the html seems to be "https://login.live.com/Me.htm?v=3" as in the dev tools in browser. Would help if you have any inputs
You cannot customize this page much, it is part of Azure AD, not AAD B2C. The only AAD branding available options are here.
And if that is not your own AAD, then you cannot make any changes, as its defined by the corporate policy of that customers AAD.