I got the same body on twelve updates in one batch two nights ago, so I have my own measurements rather than an answer from Apple. Two things narrowed it down faster than anything else I tried.
First, read the body rather than the number. Apple's published text for 4.3(a) is about multiple Bundle IDs of the same app — the "a separate map app for every city" example. The sentence you quoted, about a similar binary, metadata and/or concept as apps already on the store, is the substance of 4.3(b). Those point at two different things: 4.3(a) is a question about your own catalogue, 4.3(b) is a question about how your app reads next to what is already there. I would not raise that as a gotcha, but it does tell you which side to go and measure.
Second, measure your own side before you ask anything. It is cheap and it shrinks the surface fast:
- Byte-compare every source file against every other app you ship. shasum every file, then look for collisions. I expected to find shared files and found none: 1030 Swift files across the twelve apps, zero byte-identical pairs in either direction. That rules out "same binary repackaged" as a source-tree story and pushes the question to presentation.
- Then compare the same files by content, not just by hash. Shared filenames are not shared code. SettingsView.swift appears in 11 of my apps and averages 3.9% similarity (difflib.SequenceMatcher over comment-stripped, whitespace-normalised lines). Worth knowing before you start rewriting code that was never the problem.
- Diff your metadata. This is where mine actually was. Descriptions came out at 5.3% mean similarity across all 66 pairs and promotional text at 8.1%, both fine — but the release notes on the exact versions under review were 46.3% mean, 90.9% max, with eight of twelve opening on the identical sentence. I rewrote them to 15.4% mean, 42.3% max.
- Look at submission cadence. All twelve of mine went up inside ninety minutes from one API key. Nothing about that breaks a rule, but it reads like one template fired repeatedly, and that is a portfolio-level impression rather than an app-level one.
On clarifying with the team: Apple's own guidance is Resolution Center before an appeal, and you get one appeal per rejection, so I would not spend it before they have said something specific. I replied once, on one app rather than on all twelve, stated the measurements, and asked two questions — which app they meant, and whether the concern is between my own apps or against another developer's. Still waiting on that.
On the App Review appointment, I have not had one. There is a thread on this forum from a developer who did, and was told the match was against another developer's game in the same genre, with engine code, ad SDKs and third-party libraries all named as possible sources. So the call gave them the class of match but not the specific app. Worth knowing before you book one.
If the detail is useful, I wrote the whole measurement up here: https://thechosenvictor.com/blog/twelve-apps-rejected-guideline-4-3a-spam
