Github doesn't need to know how you implement it, just that your browser is handling it (and in this case the browser lets Bitwarden handle it lol)

I don't think that github has to know that. You could be using a password manager and choose to make it a minimum character boring password or meet minimum complexity requirements or use the same password on a million sites. You have to secure your credentials; complying with the minimums of a service isn't security.