Note: this may actually be another symptom of [bug 1005632] and there is some subtle internal intertwining. Sometimes it happens that when behavior as in mentioned [bug 1005632] is reproduced, I'll type (or may have already typed by then?) a character for the login name, and then when I press a backspace for several seconds to ensure that any characters (also displayed per expectations) are removed for sure to start from scratch, sometimes that character is like unremovable (also per visual feedback) causing the login to fail even if I am pretty sure everything should (logically) be entered correctly (subsequent retyping upon login failure works). Unfortunately, I cannot find what exact user name was attempted for that failed login, journal only indicates: > FAILED LOGIN 1 FROM tty1 FOR (unknown), User not known to the underlying authentication module I am really unsure if this should be a separate bug or it is just a sub-issue of [bug 1005632].
This is very probably related to https://github.com/karelzak/util-linux/issues/454
Fixed by upstream commit https://github.com/karelzak/util-linux/commit/2a14beb4e9c6cdf4466993741d86e45dd57ddef3
Just after-the-fact addendum: The character stuck forever is indeed actively used for the purpose of logging in, recently attested that.
This should be fixed by release v2.30.1 (f26 and rawhide).