As can be seen on this page, the section "Research Work" and "References" are collapsible while other sections are not. This is due to Mobile frontend enabling collapsing based on whether the first child element in a section is a div. On mobile, where all sections are wrapped in a div, this is not an issue, but on desktop, if the first element in a section is video for example, then that section becomes collapsible, while the others do not.
Disabling section collapsing entirely on desktop Minerva might not be desirable (not yet) because some of the TOC styling is based on the TOC being collapsible.
Maybe instead of
$heading.next().is( 'div' )
mobilefrontend could be more specific about when a section is collapsible, like
$heading.next().is( '.collapsible-block' ) ?
The toggling code should not run in this context.