Create a new gallery block. Add as many images to it as you want.
Don't change any gallery settings
Save post
The result will be the attribute columns will be 0, but the UI will show 2 (or another number depending on how many images you have in the gallery). If you change the slider in the UI to get not the default, and then save it, then the attribute columns will be correct.
What should happen:
GQL should return the same columns number as shown in the UI.
drewbaker
commented
1 year ago 
Steps to recreate:
The result will be the attribute
columnswill be 0, but the UI will show2(or another number depending on how many images you have in the gallery). If you change the slider in the UI to get not the default, and then save it, then the attributecolumnswill be correct.What should happen:
GQL should return the same
columnsnumber as shown in the UI.