When did deleting in LR mobile start deleting in Apple photos as well?

Hello @jwdave 

Please see usage details at: https://helpx.adobe.com/lightroom-cc/using/work-with-lightroom-mobile-ios.html

In short, Lightroom's new Device tab is just a view of your camera roll.  You can choose to import and edit images, which will actually bring those photos into Lightroom.  And subsequently you will be able to find those edited & imported photos in the tab called Edits for the free Lr app, and Lightroom for the paid app.  

In the Device tab, if you delete an image, those delete the image from your camera roll, as on-screen info says.  You can recover those camera roll images from the Trash in your iOS Photos app.