OK, I was finally able to reproduce this!
I asked the user to perform these exact steps (which is how I and I imagine many copy urls as text from the address bar)
In Safari's address bar, press and hold on the URL address bar at the top of the screen until the "Select/Select All" options appear.
Tap "Select All" to highlight the entire URL.
Tap "Copy" to copy the URL to your clipboard.
Go to where you want to paste the link, such as in a post or comment, and press and hold to bring up the paste option.
Tap "Paste" to insert the URL without any additional text.
He responded with his steps which were to
Tap and hold on the address bar which will pop up a menu
Select Copy from that menu
Paste into the IPS CKEditor for a PM, comment, or reply does not work
Paste into another app or a new Safari tab, etc does work
I tried his steps and confirmed it indeed does not work in the IPS Editor and does work in other places.
I then came across this Reddit topic talking about a change to Safari's Copy Links behavior related to multiple tabs, which isn't exactly the same but tells me that something changed in the behavior of the Copy Links function might also apply to the Copy function of a single link whereas there is the Title and URL as part of an underlying object schema. If CKEditor does operate in a way that doesn't recognize this object (versus the first way of simply copying and pasting text), then it would make sense nothing gets pasted: