Union Berlin started a bad form for two weeks by not getting any win. I can understand the loss versus Bayern Munich but the one against Schalke that they got a draw was unexpected. Maybe this could be a sign of another lasting bad series for them in the league but we will see. Their next game is a home one against Koln. I can't say Koln are in a good shape at all. As long as Union Berlin don't get very comfortable they should be winning this.
But I still don't expect an amazing effort until the end of the season. They would get behind Dortmund and Bayern Munich quite much at some point. But even if they finish the season in top 4 it would still be great for them.
I still wouldn't call it bad form. They have beaten Ajax in the Europa League with a strong performance. The draw against Schalke can happen, it is ok. The loss against Bayern Munich was expected even though it was a weak performance by Union Berlin. I think it comes down to the next Bundesliga game. If they lose that game I would agree that they are in bad form at least in the Bundesliga. But I think they will show a good game against Cologne.