In SharePoint subscribtion edition incoming email functionality is deprecated?

Incoming Email is available in SharePoint Server Subscription Edition, just not in Automatic mode. You will need to configure it in the Advanced mode.

Yes, it has been deprecated:

Enable incoming e-mail support for a list or library

"Incoming email is available only in SharePoint Server 2016 and earlier versions of SharePoint Server, and has been deprecated as of SharePoint Server 2019."

Sorry folks, that support article about incoming e-mail was mistaken and we've now corrected it. We haven't deprecated the incoming e-mail feature in SharePoint Server 2019 or SharePoint Server Subscription Edition. As Trevor points out automatic mode was removed starting with SharePoint Server 2019, but advanced mode continues to be supported.