It wasn't a crack - it was a bypass*, a bypass that is no longer functioning. However, Denuvo, the protection scheme that protects Doom and some other games that have been "unpiratable" over the past 6 months or so, was apparently just fully cracked.
*A bypass is different from a crack, in that, essentially, it simply fools the DRM into thinking everything is as it should be...whereas a crack removes or disables the DRM in its entirety. Bypasses are not considered to be real cracks, and often have issues - refer to the Titan Quest piracy debacle, where some of the DRM protections were bypassed, but some were (unknowingly to the pirates) not, leading to a game that appeared to have performance issues and was super buggy, which then lead to it getting bad early reviews and press from pirates...but in reality, it was just part of the DRM scheme trying to do its job.
The new Rise of Tomb Raider bypass is not a true crack either.
For now it's the only newer Denuvo game that's easily piratable.