Github dislikes email “aliases” so much that they will shadow ban your otherwise normal activities for months, and once flagged, support will request not only a “valid” email domain but also that you remove the “alias” email from the account completely.
Fuck Microsoft for buying GitHub. As expected they have made good into garbage.
GitHub was proprietary, venture-capital, Ruby sludge before Microsoft. They’d either way aim to be bought or be the next Microsoft.