w/who entry for exited TTY still being shown

[OllieGitHub]

    [host]:~ # w
    USER            TTY             IDLE    TIME             HOST
    root            pts/0           00:00   Nov 15 11:35:09  10.249.3.187
    [host]:~ # adduser testuser
    Changing password for testuser
    New password:
    Bad password: too short
    Retype password:
    passwd: password for testuser changed by root
    [host]:~ # login testuser
    Password:
    
    
    BusyBox v1.35.0 (2023-11-14 13:56:29 CET) built-in shell (ash)
    Enter 'help' for a list of built-in commands.
    [host]:~ # exit
    [host]:~ # w
    USER            TTY             IDLE    TIME             HOST
    root            pts/0           00:00   Nov 15 11:35:09  10.249.3.187
    testuser        pts/0           00:00   Nov 15 11:35:30

when the original TTY is exited, the TTY for testuser is shown as ? and seems to be cleaned up after approx. 40 seconds
(below output retrieved over serial connection)

    [host]:~ # w
    USER            TTY             IDLE    TIME             HOST
    root            ttyS0           00:00   Nov 15 11:40:01
    testuser        pts/0           ?       Nov 15 11:35:30

Sidenote: It is also unconventional/odd that the new terminal session uses the same TTY as the user from which the login was initiated.