Macbook pro M1 keychain

I have seen a case where it does that -- when I surf directly to the local IP address of one of my Routers to check on something.

Yet almost everything else seems to store the complete package of username AND password, and can spit it back when I get to that website again.

Is there something distinctive about that website or address?

In general, the username and password (such as for web sites) will be stored together as one password-type item.

what exactly are you doing, and how is this falling short off your expectations?