Also shouldnt  $sudo apt-get purge gajim    delete the config files too.

No, it removes Conffiles, that's more than 2 characters of difference than "config files"
Conffiles at face value means any file explicitly listed as such by the packager, and while the intention is, in fact, to handle a program's settings I don't think it's expected to reach into user-specific configuration* and even less so into non-configuration "application data", with the distinction between the two not always being clear or practical to implement as you can see by comparing ~/.config with ~/.local !

* It's not particularly hard to implement something such as "rm -R .config/pizza from every user's home folder", but 1- I don't think there's a mechanism to declare that as conffiles, 2- it's not an unreasonable opinion that a package manager, aka "installing a program", should not affect user files

As for the original problem I'm not sure of the direct cause but:
- You can delete your keyring from ~/.local/share/keyrings/* (but of course it could be recreated by a program trying to use it to save passwords or the like)
- Getting the login keyring to unlock, if you actually wanted gnome-keyring, is done by a PAM module (check `sudo pam-auth-update`) and/or your Xsession (check, for Xfce, applications/settings/session&startup, both the individual autostart programs and the "launch Gnome services on startup")
- It doesn't work intentionally if you autologin, this can probably be changed by screwing around with PAM options but ain't nobody got time for that (so I also consider it a nuisance like policykit/logind/etc pushed by people who think PCs are commonly used simultaneously by different people...)
- Gajim may or may not support an alternative to gnome-keyring and kwallet (ie being its own password manager, like most browsers and email clients can)

Good luck!

$ sudo apt-get purge gnome-keyring
$ dpkg -l  | grep keyring
ii  debian-archive-keyring                              2025.1                               all          OpenPGP archive certificates of the Debian archive
ii  devuan-keyring                                      2025.08.09                           all          OpenPGP certificates used by the Devuan repository
ii  gnome-keyring-pkcs11:amd64                          48.0-1                               amd64        GNOME keyring module for the PKCS#11 module loading library
ii  libpam-gnome-keyring:amd64                          48.0-1                               amd64        PAM module to unlock the GNOME keyring upon login
ii  python3-keyring                                     25.6.0-2                             all          store and access your passwords safely

I'm not sure it's related to my issue. For example google-chrome presents the same message and gajim (if purged (and its .config dir)) and then if i started again after i try to enter my account for a server the same message will appear. If i hit cancel the dialogue dissapear but my xmpp acoount wont still login.
If i choose yes i get a dialogue window:

If i manage to login (without enabling kde waller -- yes that happened!) the next time i start gajim i get near my xfce notifacation area the message 'password not found authentication failed' and although i can see my contacts i am offline and trying to get online i get the same notification message.

Also shouldnt  $sudo apt-get purge gajim    delete the config files too. I purged it. I reninstalled it and my contacts were there.
Indeed:

~/.config/gajim$ ls
pluginsconfig  settings.sqlite  theme

ps: it not my writing that is messed up..  :-)

Ditto.

Best,

A.

Probably caused by gnome-keyring. I always found it useless, annoying and glitchy - it's one of the things I remove immediately after OS installation.

Guaranteed. I get rid of it too.

When i start Gajim i see:

The same message i see starting google-chrome