I just came across this modal from Airbnb with a different close button position. It is normally on the right but I wonder what's the reasoning behind this.
I suppose it is for consistency. They decided to the main button on the left and the button placement does not break natural human behavior, where “yes” is followed by “no”. Even in dialogs, it is better to align buttons right, a lot of platforms prefer to keep the left alignment for consistency. StackOverflow has the same position for buttons.
The only reason, I can imagine is prevent user errors, like accidental click.
You can read more about here: https://www.nngroup.com/articles/user-mistakes/
I assume this is based on how they want to users to read the actions.
Once the user is done filling out the form, the first thing they will encounter (either F or Z reading pattern) is the option to "Save". That's the primary action. The designers probably did not want to have the users encounter a "Cancel" button first when the user's intention is to save the values they just entered.