TÜV for vehicles is in Germany rather strict, and when you change something substantial/physical at your vehicle you lose the right to drive it on rublic roads
https://www.spiegel.de/politik/deutschland/boris-pistorius-erhoeht-im-streit-ueber-leopard-reparaturzentrum-den-druck-auf-polen-a-13304150-0d46-4748-aedd-57ae67faa2d1?sara_ref=re-so-app-sh this is my source, i dont know If any english newsside picked it up yet
The tank did continue driving.