It used to work just fine until a few weeks ago.
They changed the website layout slightly so now only
copy&paste works.
When I search for login data it also shows sites were
I used web or gmx e-mail adresses as login which is
kinda annoying.
The login for the new Web.de layout is very simple and works with a default KeePass entry like this
{USERNAME}{ENTER}{DELAY 1000}{PASSWORD}{ENTER}
The new GMX/web.de login puts the password field inside a shadow DOM web component, which Kee couldn’t see. I’ve opened a pull request that fixes this: Detect and fill login fields inside open shadow roots by blacksun80 · Pull Request #348 · kee-org/browser-addon · GitHub
Until it is merged and released, the auto-type workaround above still applies.