Sure. Many cases, complex thing. Still, if a user enters special, undiscoverable URL, which happens to be 404 invalid, DAVdroid shall communicate this to the user and not try the .well-known addresses.
I am addressing the raised concerns here, stating in which cases 401 means invalid username/password. E.g. when the .well-known/ addresses are not fetched and thus no 404 comes from them.
An additional wrong username/password on 401 is an improvement, but I think in some cases it can mean only this and not lead to a misleading ”Couldn’t find CalDAV/CardDAV service“.