The presence of the collapse styles on the #ug-header element is causing an extra aria-expanded class to be added. This is due to extra javascript in ug-script.js that originally added aria-expanded for cases where it was not being applied automatically.
Two options:
(Simpler) Possibly remove the collapse style from #ug-header (particularly if it's not a collapsible element). This way A11y tools will not expect it to collapse when it's not meant ot.
(More complicated) Look into the ug-script.js and determine if it is still necessary.
The presence of the collapse styles on the #ug-header element is causing an extra aria-expanded class to be added. This is due to extra javascript in ug-script.js that originally added aria-expanded for cases where it was not being applied automatically.
Two options: