Extended header on SharePoint page shows double?

Question

Hello all,
I have received a question from a colleague to ask another party to see if anyone knows about this issue and know how to resolve this?

Problem:

On a certain page (home site) there is a small line visible and when enabling "Change the look - Header - from Standard to Extended" we receive a double hub navigation bar.

Standard Header Layout: (the left one is where the extra line is visible)

Extended Header Layout: (here you can see the black bar comes above the regular navigation bar of that certain page)

Would anyone have encountered this issue before or know how to possibly resolve this?
Kind regards,