The entling on the left is much larger than the other entlings but is still called Entling. Shouldn’t it be called Ent, or do Entlings have different sizes?
Edit: Also this guy was much tougher than the smaller ones, so he should be called Ent in my opinion.
As @Wiese2007 says, it’s just a different size of Entling. Same happens with wolves and the giant zombie
So, it’s not a bug. But next time, could you click on them and verify the info on the unit frame? They added lots of new monsters and encounters, so there can be bugs for sure.
Sometimes I find myself clicking on their portraits, wanting to know their stats, to have an idea of how much more dangerous they are compared to the other monsters