That is not what their wording says. They could have said "code that is mostly covered by copyright under German law", but they chose to say 'mostly consist of code written by "generative AI"-tools'.

Also, if you are a non-German user of Codeberg and there is a wide difference between what is covered by copyright in your country and Germany (e.g. if you are British) this might make Codeberg less of a suitable choice for you. What copyright laws matter to a particular user? Their country, the US because of its dominance and reach, or some sort of global safe/effective compromise?

This has the feel of being done by people who do not understand how to work things to be clear legally, nor of an understanding of the consequences.