There is a small bug occurring in the new Nav Mega Menu block, specifically with the Modal → Off-canvas → Placement right. Specifically, whenever I enable the off-canvas feature for the display mode on tablets and mobile devices, the layout of the structure breaks. This issue does not occur with the Placement Left option.
@NHViet, As a temporary workaround, you can try setting overflow-x: hidden on the root container, either the body or html element or depending on your template, one of the other containers you use. This should resolve the issue for now.