Despite the claims of many a Marvel fan, a tragic scene at the end of the Doom Patrol episode "Flex Patrol" is not a blatant rip-off of the ending of Avengers: Infinity War. While there is a striking visual similarity in how the characters' bodies slowly dissolve to dust, the scene is taken from a DC Comics book from 1991.
The most recent episodes of Doom Patrol have seen the residents of Doom Manor searching for Flex Mentallo - a cereal mascot from the 1950s, who seemingly stepped out of a comic book advertisement and into the real world. The penultimate episode, "Flex Patrol", revealed something of his life and how he married a woman named Delores and became an honest-to-goodness superhero, utilizing his mastery of the power of Muscle Mystery to protect his community. He apparently did this for several years before being abducted by the sinister Bureau of Normalcy - a government organization tasked with containing or destroying anything that defies convention, for the good of The American Way.
The latest Doom Patrol also saw Flex being freed from the Ant Farm - the Bureau of Normalcy's secret research and development facility. Unfortunately, once the team was safely back at Doom Manor, they discovered that Flex had amnesia and seemed to care about nothing more than his favorite soap operas after decades in captivity with nothing but television to occupy his mind. Thankfully, Crazy Jane was able to locate Flex's long-lost wife Delores, who had been abducted and brainwashed into becoming a Bureau of Normalcy agent. The sound of her laugh was enough to restore Flex's mind and powers, as his smile restored her memory. Unfortunately, just after they hugged for the first time in decades, Delores began to crumble into dust - a fail-safe the Bureau of Normalcy had installed within her to prevent her from getting too close to Flex, when she was still trying to fight her programming.
Despite the digital effects being similar to those utilized to depict those people killed by Thanos' snap in Infinity War, the death of Delores in Doom Patrol is taken directly from the original comics. Here, Flex Mentallo confronted the Men From N.O.W.H.E.R.E. (the group that was adapted into the Bureau of Normalcy in the show) and just barely escaped with his life, losing his mind and his powers in the process. He wandered the Earth for several years before being rescued by Danny The Street, recovering his memory after he saw the Men from N.O.W.H.E.R.E. fighting the Doom Patrol. It was shortly after this, in Doom Patrol #43, that he was found by his old girlfriend, Delores Watson, who gave him his old costume before she began crumpling to dust. With her dying breaths, she revealed that the Men From N.O.W.H.E.R.E. had been forcing her to search for Flex for decades so that they could recapture him.
While it is easy to see how comparisons could be made between the visuals of how Delores dies in Doom Patrol and the many heroes who died in Avengers: Infinity War, it is unfair to say that the former ripped off the later. Marvel Studios does not hold a monopoly on the idea of people crumbling to dust when they die; and the Doom Patrol comic in which it first happened released several months before Infinity Gauntlet #1 where Thanos first snapped (and the impact was spontaneous vanishing, not "not feeling so good" and becoming dust). The accusations are ironic, however, given the belief of many comic book historians that X-Men started off as a rip-off of Doom Patrol.