Mortal Kombat 11 features a deep roster of characters, each with their own unique strengths and weaknesses. Many fans understand that this configuration is necessary in order to create interesting counterplay in MK11, and the game would not be particularly compelling if every fighter excelled and failed in exactly the same way. That said, there is the expectation of a level of consistency across the roster in full, and indeed there is something about Sub-Zero that goes against that.
Specifically, of all of the downward air projectiles in Mortal Kombat 11, only Sub-Zero's is not reflected by Nightwolf's Reflector special move. This phenomenon can be seen in the video found below, and while the advantage it gives to Sub-Zero is narrow enough not to create any major balance problems, Polar Axe's ability to bypass Reflector is a strange inconsistency that may surprise some fans.
For the uninitiated, Polar Axe is a special move present in Sub-Zero's Thin Ice tournament variation. This Mortal Kombat 11 variation also features Slide, a long range low attack, and it is one that some players find extremely obnoxious. Indeed, this is a sentiment that can be seen reflected in the Reddit thread where this detail about Polar Axe was recently shared, with fans turning up to voice their disdain for Thin Ice.
That said, there are players that are not taking issue with Thin Ice in general but are suggesting that the advantage Polar Axe has over the rest of the cast's air projectiles should be rectified. "It should absolutely reflect the air axe," one Sub-Zero main writes of Nightwolf's Reflector, and this is an opinion that many in the thread seemingly share.
With respect to why Polar Axe is the only projectile not reflected by Reflector, that it is not currently known. Perhaps the axe's advantage comes from the fact that it is formed out of ice, or maybe it is simply a bug to be addressed in a forthcoming Mortal Kombat 11 patch. Whatever the case may be, Nightwolf players should look towards block instead of Reflector when going up against a Thin Ice Sub-Zero for the time being.
Mortal Kombat 11 is available now for PC, PS4, Stadia, Switch, and Xbox One.