I have added a GeneratePress Container block and set it to full-width.
The problem is that it creates a horizontal scrollbar if there is a vertical scrollbar present and not otherwise.
However, this is not happening with Beaver Builder. If I add a Beaver Builder module and set the container width to full-width, the container does not overflow irrespective if there is a vertical scrollbar or not.
To further debug this issue, I tried this with Astra theme and couldn’t reproduce this issue.