Hi there,
I believe this is a bug in Beaver Builder which adds the BB class to the body on the blog/archives/search results if one of the pages/posts has BB enabled.
In the next version of GP, we will only make things full width with BB if the layout is set to no sidebars, which should fix issues like this.
For now, try this CSS:
.fl-builder .container.grid-container {
max-width: 1250px;
}
.no-sidebar.fl-builder .container.grid-container {
max-width: 100%;
}