There can be several technical reasons why users encounter alternative addresses, including regional availability, infrastructure changes, domain changes or temporary access problems. However, seeing an alternative address does not automatically mean that it is authentic. I would treat every new domain as something that needs to be verified independently. For example, you can use a reference here to gather additional information, but I would still check the exact domain before entering any account details. I also recommend avoiding shortened links when possible because they hide the destination. If an alternative address redirects somewhere unexpected, I would simply close the page rather than continuing.