If the money already belongs to you (and you can prove it), I don't think the transfer would be relevant from a tax point of view. Some countries do have a wealth tax (and actually transfering the money into the country might alert the tax office of previously undeclared wealth) but that's not the case (anymore) in Germany.
Furthermore, if we are talking about tens of thousands of euros, the transaction might be flagged by the bank and reported to the relevant financial intelligence unit. Based on a quick Google search, it seems that in Germany banks have to perform some due dilligence and keep a record of your identity (but not necessarily report it) for any transaction above €15000 so I guess it would make sense to approach them beforehand.