Die Linke which is the most Left-Wing party and is currently below 5% in the polls. Especially after the split with BSW which is very socially Right-Wing and Conservative. (Also Die Linke is also very Pro-Israel.) In France the Left coalition got the most seats (They did not get the majority or got in power but they still did very well in the elections.) And in most other European countries the Communist Party (Despite many of them being eurocom/revisionist (KKE/PCE/PCF being specifically)) has done major success in their [insert] country but in Germany the DKP is just a fringe minor party.
Die Linke gained more than 10.000 member this year alone so we are seeing a small gain in their popularity and polling around almost 6%. of course that is in large because there will be elections soon.
it is true that the DKP is a very small party at the moment. 50 years ago they had i think about 60.000 member. right now they are not gaining much influence, but they are very well read and active communists.
the only thing german communists can do is join the dkp and organize in unions and their workplaces as well as on the streets, with the guidance of the party.