Hi Peter.
Old issue. Not related to margin/padding.
SPPB articles editor contains an outdated value of the container max-width based on Bootstrap 4 rules. There is not 1400px breakpoint with 1320px value by default.

To fix this, set up the max-width of the container to 1320px in the section settings.

Hi Ziaul Kabir.
You should add this to a bug list to fix in the next update.
And addition, there is another bug. If you activate the Column Alignment option, the Stretch Section option stops working correctly - the container begins to stick to the left border of the browser (in live view).
As an employee of support, you should learn to work with Dev Tools and study your own products well so as not to waste user time on unnecessary provision of access.
Since you are a beginner here, I hope you quickly increase your skills. Unfortunately, some support officers cannot increase their skills for years, which leads to a poor service rating.