Please explain what are the results of the changes~:
screenshot before and after.
For me here it breaks totally the display
when collapsed, the table disapears
when not collapsed, the table displays below the sidebar

The reason we have these 2 closing divs for the moment is that the filters are not added to the sidebar.
Therefore was added a custom layout /sidebars/submenu where they are absent.
Once we have modified the code to be able to use JHtmlSidebar::addFilter(), we will be able to correct this.

We need to take care of this once joomla/joomla-cms#4450 is sorted out.

obsolete