We have an Open Data Site, where we both have ArcGIS Online hosted ArcGIS REST services and ArcGIS Online hosted WFS services (made from the REST service item in ArcGIS Online):
The layers are shared to the public and to our ArcGIS Open Data group.
Howerver, its only the ArcGIS REST services that are shown in the Open Data page - there is no WFS.. Notice the Content Type overview to the left, where WFS aren't present:
Going to the hub administration page, the WFS services are there:
And i can see from a guide we made previously, that it has been on the Open Data site earlier (june 2020)
So, why are WFS services not shown on my Open Data site anymore?
WFS items are categorized as a Map and can be found under the Apps&Maps collection. I would check under this collection or the 'All' collection. You can also manually specify a filter like content type by adding on a query parameter to the URL. So try adding navigating to ```<your site URL>/search?type=wfs```. If the results still aren't found, I suggest removing the WFS from the Content Library (what you described as "admin"), republish the WFS, and then try re-adding them to your site.