Being asked to login via an “internal login page” is a huge, bright red flag. It doesn’t matter what the reasoning is, if it’s not the same domain or an SSO int

Being asked to login via an “internal login page” is a huge, bright red flag. It doesn’t matter what the reasoning is, if it’s not the same domain or an SSO integration that is well known to both you and the vendor then you shouldn’t be using it. This is security 101 type stuff.