Just logistically speaking, imagine needing to send dozens of different types of dozens of spare parts to different sections of a thousand-mile wide front line, with different types, shapes and calibers of ammunition as well. These tanks will likely just be abandoned after they get even slightly damaged.
There was a report recently that even if Germany decides to send tanks, they won’t be ready before 2024.
The German military is absolutely useless. The kit doesn’t work and the soldiers are right wing extremists. It’s in such bad shape that the €100B in additional military funding approved in 2022, more than double the standard annual budget, won’t even suffice to get the Bundeswehr into fighting shape.