From Adi Robertson in The Verge:

The Enola Holmes case hinged on Sherlock Holmes’ complicated copyright status. Most Holmes stories sit in the public domain, and stories like Enola Holmes — which reimagines Holmes (played by Henry Cavill) having a younger sister — can freely repurpose their elements. But 10 of Arthur Conan Doyle’s stories are still protected by copyright, and the Doyle estate argued that they depict a meaningfully different version of the character. (He’s more caring, less overtly contemptuous of women and friendship, and generally less of a jerk.)

I don’t believe Arthur Conan Doyle’s estate should have any rights over Sherlock Holmes at all. Conan Doyle died in 1930. It’s completely outrageous.