Sorry, I don't speak german so I'll speak english instead.
I think there's a small hardcoded text in IP.Tracker. I have posted a bug report about this at IPS. I made a small fix too.
If IPS confirm this bug, this line will have to be modified in lang_tracker:
'bt_project_rss_channel' => 'Problemreporte von [url="https://www.invisionpower.com/clients/index.php?app=nexus&module=promotion§ion=referral&id=5636&direct=aHR0cDovL3d3dy5pbnZpc2lvbnBvd2VyLmNvbS8%3D"]Invision Power Services[/url]',
To:
'bt_project_rss_channel' => 'Problemreporte von',
(Don't you find it strange that every RSS feed will have a description saying the feed is comming from IPS?)
Let's see what IPS will say about it.