Solved

Are we going to Level 21 now?

Just notice on my Technology building that you can see covered in white level 21 as the next level. Did I miss something? 

Sorry for the slow response. 
As far as I am aware, level 21 is not being added at the moment. Maybe this is like the situation once you reach level 20, it says XP until next level, even though 21 doesn't exist yet.

Thanks Connor.