Why did candy crush soda 2166 change from 30 to 20 moves?

@LauraLMason,
oh dear, I just checked back. It is not the worst one... bad enough, yes.
But get a bit further and you will find worse. 
I spent hours getting boosters -I'm lucky, I got the quests back, to use them again on a hard level. A striped and a 2 pinks were needed, and I was afraid it would not work...
I'm stuck at 2194, after some truly horrible levels. 2197 was terrible, and another around 2090...
I am out of boosters for today, but the problem is the number of shots. How to deal with it? no idea.
I feel for you.

Having same problem with level 2175. Only 20 moves but all help videos show 30 moves 

If you see videos online showing more moves, this is the reason.  The videos are outdated because the video creators make them when the levels are first released.  The studio monitors all levels when they are released and they check to see how many players clear a specific level and how long it takes for them to clear it.  If it's too easy or too difficult they will "tweak" the levels a bit.  The video creators can't keep up with the studio changes so you are still only seeing the first video release.  You can read more about it here:  https://community.king.com/en/candy-crush-saga/discussion/249891/has-your-level-changed/p1?new=1