Just to be clear, the version of "Shadow of Your Love" released as a single from the Appetite is not just a different mix from the previous versions. This is entirely new, later, different recording.
The three versions were as follows:
"Live" version: This version was actually recorded at Pasha Studios and had audience noise overdubbed. It appeared as a b-side to the "It's So Easy" / "Mr. Brownstone" single and also on the 1988 EP.
Sound City version: This was recorded as part of the Sound City sessions, which means it was actually recorded before the the above version. It was issued on the "Live and Let Die" single, and on some versions was tagged with a "live" signification which was odd as there is nothing identifiable about the recording being live, but maybe it was all recorded at once with no overdubs making it technically true, I don't know.
2018 single / Appetite re-issue version: This was recorded with Mike Clink as apparently a kind of test to see if a collaboration between the band and him would work. This version is my favorite of the versions and honestly sounds like it could have been recorded yesterday. And maybe it was extensively tinkered with shortly before its release? If it was, I suspect we'll never know. I personally don't think anything was added instrumentally or vocally but that the remix was pretty extensive and brought out and/or pushed back things in the mix that might not have had the same choices in '86 or '87. But who knows?