Link in event description is set wrong

Hej,

I try to set a link in an event's description but the builded link is wrong.
I want to reach this site:
/de/service/downloadbereich.html
which is the same as:
index.php?option=com_content&view=article&id=103&Itemid=244

but when I choose this site by link manager /menu the result links to this one:
/de/service/kalender-termine-monat/Monatskalender/2020/index.php?option=com_content&view=article&id=103&Itemid=244

The calendar itself is placed here:
/de/service/kalender-termine-monat.html

Seems the link manager doesn't work properly?

Thanks in advance.