D12 is a curio in the hip hop world. More often than not, a group becomes successful, a member becomes a breakout star, and then said member goes solo. The opposite proved true with Eminem. The legendary Detroit emcee was a founding member of D12, but he gained success as a solo act before helping to elevate the global profile of the group. Then, he left.
Eminem was a member of D12 from 1996 to 1998, became a megastar the following year, and then rejoined the group for the studio albums Devil's Night (2001) and D12 World (2004). The group scored two sizable hits with "My Band" and "Purple Pills," but Eminem's decision to walk away has left D12 in sort of a cultural limbo. The group is still active, but they are more famous as an Eminem side project.
Eminem distanced himself from D12 in 2006

Eminem was technically part of D12 until 2018, but his diminished involvement in the group can be traced to over a decade earlier. The death of founding member and close friend Proof in 2006 was a shock to Em, and it coincided with the rapper's addiction issues. Eminem only appeared on two D12 songs after 2006, and the latter, "Trapped," made specific reference to Proof's death.
Eminem's inactivity went remarked upon for most of the 2010s, but the rapper himself confirmed he was no longer part of D12 on the song "Stepping Stone." He recounts his experience recording with Proof and the rest of the group, and how he ultimately used D12 to boost his solo career instead of helping the others achieve mainstream success.
D12 continues to perform as a trio

Em also declared that D12 was defunct in the song's final verse. "The longer we spend livin' this lie that we live, the less is left for closure, so let's let this go," he raps. "It's not goodbye to our friendship, but D12 is over." Slim Shady decided to close the book on the crew that scored their biggest hit by riffing on the discrepancy between his success and theirs (the aforementioned "My Band").
D12 may have been over for Eminem, but it continues to be an active group today. Founding members Bizarre, Kuniva and Swifty McVay opened up for Snoop Dogg during his 2023 tour, then they performed a series of shows to celebrate the anniversary of their second album. Eminem, the late Proof, and Kon Artis are on the short list of founding members who are no longer involved.