Trouble with Admin Email Verification Screen

When logging in as an admin I get the new Amin Email Verification Screen as expected. When I click the button that the address is correct I then get a new login screen showing errors ERROR: The username field is empty. ERROR: The password field is empty.

So in order to get in I have to click the button to update the email address. However the verification screen shows up every time I login.

I want to turn off the verification by using the
add_filter( ‘admin_email_check_interval’, ‘__return_false’ );
As found on page https://make.www.ads-software.com/core/2019/10/17/wordpress-5-3-admin-email-verification-screen/ but it doesn’t say what file or where to put the entry.

If anyone could help with either one or both of these issues it would be appreciated.