That doesn't mean fakes in Contax mount don't exist.
Yes - actually there is one model that exists, it's the famous
C a r l Z e i s s J e n a Sonnar 5sm 1:2
which was sold altogether with Kiev bodies painted black and disguised into Contax bodies with a bad Carl Zeiss Jena logo stamped on the frontplate near the focusing wheel.
But this attempt has been so pityful as a fakery that everybody could notice that this was a fake.
I also remember a very few Jupiter 3 lenses in Contax RF mount wearing a genuine prewar CZJ frontplate, but those were very distinguishable (different barrels).
This very fakery market didn't match many customers and those lenses remained for sale for a very long time, unsuccessfully. On the contrary, the market for fake LTM Sonnars remained quite dynamic, people seemed to want to gamble hoping that the cheap lens they would receive in the mail would turn out to be a genuine Zeiss one eventually.
I'd say that onwards from now, almost 100% of the Sonnars in Contax mount you will find at auction are genuine ones, whatever model they are, while more than 95% of the Sonnars in LTM will be fakes.
And remember - nobody can tell for sure that Carl Zeiss Jena actually manufactured some Sonnars in LTM, most of the "genuine" LTM Sonnars rather being some contemporary aftermarket conversions made in German workshops, either for military purpose or to answer to special customers demands.
There is also that "ZK" thing - with the same legends and the same fakeries.