About six years ago there was a publication summing up the current state of affairs[1]. I believe we can safely say your comment doesn't reflect it at all.
[0]: https://www.gesetze-im-internet.de/gg/art_14.html
[1]: https://www.bundestag.de/resource/blob/414774/826f537e22a405...
Maybe that's a technicality (at first glance it feels like an almost outlandish claim), but in the spirit of enquiry I'll put it like this: can you share a source for that?
FWIW I skimmed [0] and failed to come up with anything that comes close...
https://de.wikipedia.org/wiki/Enteignung#Wiedervereinigtes_D... (third paragraph):
Since 2009 there have been 1647 procedures initiated in the Bundesrepublik for expropriation of landownership for road construction projects. As of August 2020, 448 of these procedures have been completed. Paragraph 19 of the Federal Funeral Street Act allows expropriations, "insofar as they are necessary for the execution of a determined or approved construction project" and are in accordance with Article 14 of the Basic Law for the benefit of the general public.
Note that private property rights still exist on top of that but this is why the state can decide that e.g. an energy company's interest in your land is more beneficial to the people than yours. You'll still get reimbursed although legally speaking I'm not sure the state would have to do that in order to seize it. The difference is that they couldn't do this for land owned by the Catholic church for example.
As a caveat note that not all land used by the Catholic church in Germany is owned by the Catholic church, this really only applies to historical claims and contracts the state decided to uphold.