Today 04/09/2019, I noticed that there is a new v.4.1.0 version of the Experience Cloud ID Service extension for upgrade. Before doing an upgrade, I want to read the extension's release notes.
When I went to the Experience Cloud ID Service extension's release notes page (linked below), it only has info for v3.1.0. When I click the "Extension Info" item in the extension's "Configure" dropdown, I get an "App not found." page within the Adobe Exchange (linked below).