To borrow a quote from another Disney-owned franchise for a moment, Ant-Man and the Wasp: Quantumania was supposed to be The Chosen One — the movie that would rescue the MCU from the doldrums it had got stuck in during Phase Four. As it happens, though, the trilogy-capper has gone down worse than all but one of Phase Four’s entries to be declared the joint-worst Marvel film of the lot. This is far from the auspicious start to Phase Five we were banking on.
In fact, Quantumania is so bad that it’s failure is just bringing to light how arbitrary and meaningless the MCU’s phases are. One popular tweet from Twitter user @blurayangel put the call out to the Marvel fandom to name their “least favorite MCU Phase 4 project,” with the pictured options including such controversial releases as Thor: Love and Thunder, She-Hulk: Attorney at Law, Doctor Strange in the Multiverse of Madness, and, incongruously, Quantumania.
Obviously, there were a lot of responses from card-carrying MCU experts who couldn’t abide this error…
… However, many others likewise didn’t see much of a distinction between Phase Four and Phase Five’s opening chapter, admitting that it probably would be the worst of the bunch if it did count.
The OP may well have known what they were doing all along here, and deliberately dropped in this error to annoy the more pedantic fans out there. On the other, if it’s a genuine mistake then it just makes clear that Phase Five is nowhere near the fresh start for the franchise the MCU needed. Maybe this middle phase of the Multiverse Saga will build its own identity once the likes of Loki season two and Guardians of the Galaxy Vol. 3 roll around.