This has happened a few times before to Niko as well(although he usually still dominates banana) and I dont really think its Niko playing poorly or doing anything differently than he does when hes dominating the position.
I think what has happened is ever since G2 started dominating on Inferno, a lot of top 10-15 teams have done A LOT of VOD review on G2s inferno and specifically looking at how they can stop Niko at banana because its a such an important position to control on the map, whenever Niko is farming on banana its positively correlated with G2 winning the map like 95% of the time. So teams that have the skill, and that have done their homework are just anti stratting Niko at banana.
But I also think that Banana is just one of those positions where aspects of luck and timing really make a bigger impact than usual. If you watched Niko today against VP on banana, half the time he was dying, it was basically just bad luck/timing(like he never was going wood pile on T side...and the one round he does, VP somehow double nades him despite everything being smoked off).