Plz explain X-axis transformation when using Stacking

Sorry, new here:

Can someone explain the transformation that my x-axis is undergoing when I use the stack option?
It looks like it’s a % maybe? I appreciate any resources you can give.


X-axis is a Log10 value

5vs5 dot plot test1

After stacking X-axis is a value is 0-100

Stacking 5vs5 plot