I think it's games from a specific company.
The charecter of Shelock Holmes is in the public domain, and anybody who wants to make Holmes game can do so.
But the indivdual Holmes games are still under copyright, and can have licence issues.
It's long to talk about a Holmes franchise;you have competing Holmes franchises.

Speculation follows:
From the info I was able to gather, the IP seems to belong mostly to Frogwares currently (which I don't understand, as Sherlock Holmes is in the Public Domain, so it might be something with trademark stuff?), so there should be only two games at risk: The Devil's Daughter and another one. Both by Nacon.
If the guy who wrote about the removal was not wrong, it likely is tied to their battle over the license rights that started in August 2020.

Sorry that I have no info myself.