You can see here for example https://youtu.be/mKn4Pi3qXjU?t=3594 that members of the Bundestag holding cards up during a vote on a bill. Is this a special kind of voting? How does it work?
The use of cards is a rule designated by Rule 52 of the Rules of procedure to document members who don't participate so that they can be fined for not participating. The normal voting procedure (that is the one NOT designated by Rule 52).
allows precise figures on the results of the vote and the majorities obtained to be recorded, but does not indicate which Members were absent. It is therefore common in parliamentary practice for a vote using voting cards bearing Members' names, in accordance with Rule 52 of the Rules of Procedure, to be demanded in such cases. Under this rule, instead of the vote being taken by a show of hands, all Members cast their votes using a voting card bearing their names and their vote ("Yes", "No", "I abstain"). The name of each Member together with his or her vote is then published in the stenographic record of the sitting. In addition, Members who fail to participate in a vote of this kind are penalised by having a certain amount deducted from their expense allowance.