Germany won't block Poland giving Ukraine tanks.
Good!
They should send Leopards of their own, too.
Frankly, the reasons advanced against giving Ukraine the Leopards are stupid. Here's a few of them:
Tanks aren't effective anymore.
They have their flaws, but are still vital elements of large-scale ground offensives. An army trying to advance without tanks becomes more vulnerable, not less. Ukraine made good use of old Soviet tanks in their offensives in the fall. The Leopards and other Western tanks are much better.
Germany shouldn't send tanks because of its role in World War II.
If taken seriously, this means Germany shouldn't send Ukraine any weapons at all. There is no principled distinction between tanks and, e.g., artillery. But ultimately the sins of a wholly different generation of Germans 80 years ago do not dictate what is right for today's Germans (or anyone else) to do now. If you want to argue I don't appreciate the evils of the Nazis enough, I will merely note I lost multiple relatives in the Holocaust. While Putin is not as bad as the Nazis, his authoritarian, expansionist nationalism and irredentism has much in common with theirs. Beating him would strike a blow against it.
Russia will escalate if tanks are sent.
No reason to think they will do so more if tanks are sent than if they aren't. They are already doing everything they can to win, short of moves that would bring direct NATO involvement in the war (e.g. - attacking NATO countries, and/or using nukes). And strengthening Ukraine won't make them more likely to do the latter, because Putin well knows that it's a bad idea to add to his list of battlefield opponents when forces can't even handle Ukraine's military.
There are some other arguments that have been made. But they're even worse than the above. So I will call it a day, at least for now.