I don't know if this is a JED team issue, a Install from Web plugin issue or what but The install from web plugin is only displaying extensions that are marked as compatible with joomla 4 alpha. It is not including extensions that are marked as compatible with Joomla 4 Beta

To make it even harder to find extensions you will also see that extension on JED are shown with a 4Alpha tag on search views and then (where appropriate) a 4beta tag on the individual item view.

So I suspect that there are multiple bugs here