Well, after a pretty bad October, plugin sales on Fab seem to have recovered, so that's good news. 🥳
Interestingly I've noticed that in the last week or two the Epic Launcher has started installing Fab plugins in a different folder, appending the UE version to the plugin folder, e.g. Engine/Plugins/Marketplace/YourPlugin_5.4. I wonder if this is a precursor to installing engine plugins outside the installed engine folder (e.g. Program Files/Epic Games/UE_5.4)