Dwayne Johnson's argument about the financial success of Black Adam, despite the initial failure of The Flash, seems to have some validity. Following the Discovery merger with Warner Bros., the WBD CEO made significant changes, such as putting Batgirl on hold and replacing the previous WB President. Despite the financial disappointments of Birds of Prey, Wonder Woman 1984, and The Suicide Squad, Black Adam, which belonged to the previous WB regime, was still moving forward. This could be attributed to the fact that the latter two films were released simultaneously on HBO Max due to the pandemic, and also because they marked the flawed start of the DCEU soft reboot. Therefore, Black Adam needed to impress the new WBD CEO in order to support Johnson's vision for his part of the franchise.
Despite surpassing the previous three DCEU films in terms of performance, Black Adam still faced criticism. However, with the combined revenue of Shazam: Fury of the Gods and The Flash matching Black Adam's financial performance, some are now reevaluating its failure. The film's success seems to be reinterpreted as it achieved a global gross of $390 million without a release in China. These details may not have been significant to WB due to their reluctance to continue with the Snyderverse, even though Black Adam marked the return of Henry Cavill's Superman since Zack Snyder's Justice League, going against WB's plan to recast the character. Arguably, studios don't invest $190-260 million to earn only $52-$72 million in profits, especially considering that there were disputes over Johnson's reported figures (via Puck).
Looking back, Black Adam's success or failure may not be as clear-cut compared to The Flash's box office performance. Both Shazam: Fury of the Gods and The Flash experienced a decline that can be attributed to various external factors that some fans believe have had a negative impact on the brand's success. These factors include WB's decision to release and support the theatrical cut of Justice League, labeling Zack Snyder's Justice League as a "cul-de-sac" upon its release, Batgirl being axed by Zaslav, DC Studios CEO James Gunn's announcement of another soft reboot, and the overall shift in the industry's business model from art to content, exemplified by the rise of streaming alongside the traditional theater experience.
Black Adam's situation, involving the conflict between Johnson and WB, is just a part of DC's decline, according to some fans. It is believed that this decline started with WB's decision to cut 30 minutes from the theatrical release of Batman v Superman in hopes of increasing its profitability. However, this move backfired, resulting in negative reviews and causing the studio to further interfere with subsequent DCEU films. Currently, DC's future appears grim as the studio is burdened with a $49 billion debt and a ongoing writers' strike, which WB may be held accountable for. Unless projects like Blue Beetle, Aquaman 2, or Gunn's DCU can turn things around, the outlook for DC remains uncertain. Meanwhile, The Flash is currently being screened in theaters.
Source: MyTimeToShineHello, Dwayne Johnson, Puck