Removing and then re-adding the same dependent caused my tax bill to increase by $1.5K

I just completed my 2019 return today and owe $3,400.  I am claiming 3 children on my 2019 taxes.  I wanted to see what the difference would be if I only claimed 2 of 3 children.  By only claiming 2 of 3 children, my tax bill increased by over $2K, so I re-added the same child back to my return to claim all 3 children.  However, my tax bill did *not* to the original amount of $3,400.  Instead, my tax bill jumped to $4,200.  Any ideas what could have caused this.  I re-entered the exact same information, so my tax bill should have returned to $3,400.  

 

Could this be a glitch in the Turbo Tax software?

 

Appreciate any advice you might have.

 

Thanks,
Jason