SharePoint Quick Launch Navigation – Missing Header Option

Working a client today, I stumbled across a weird "feature" of SharePoint Online sites that's directly related to a head-scratcher related to SharePoint hub sites. It has to do with adding a navigation item to the quick launch menu. More specifically, SharePoint Online Quick Launch Missing the Header option. We had had to SharePoint Online sites, modern UI, both created without Office 365 groups. We tried to add a navigation item to each of them and had these two different options.