The Fanastic Four will premiere in July 2025, but it won't be set in it's year of release. Instead, it takes place in an alternate version of the 1960s. This comes with a completely different aesthetic from the MCU, which is reflected in the designs of the team. As a result, the designs once again are not comic accurate. This term, often thrown around when adaptations don’t resemble specific source material, can be subjective -dependent on which comic Joe Audience (read: the general audience member) deems the definitive source. And comic accuracy isn't the only type of accuracy that takes precedence.
Another kind of accuracy often observed in movie designs is historical accuracy, which doesn’t necessarily refer to strict factuality but rather to the evolution of historical elements. For instance, while the depiction of sharks swimming in a flooded Colosseum in GladIIator is not historically factual, flooding it aligns with the Romans' advanced understanding of hydro-engineering. So, it is still believable that the Colosseum was flooded. In short, historical accuracy is the understanding or knowledge of historical development, whether the history itself is factual or not.
Historical accuracy
This understanding can also be applied to Fantastic Four. Set in a retrofuturist 1960s, this interpretation explains deviations from comic designs. The history being different, means fashion is different as well, since fashion is often closely related to history. For example, fictional works like Game of Thrones also use historical inspiration for costumes, drawing from real-world patterns in embroidery and courtly attire to ground their world in a semblance of realism. So, Fantastic Four might not be comic accurate, but that's in part due it having a setting where it wouldn't make sense in.
Still, this accuracy is not always followed. The MCU is a massive universe, which is why it can be distracting. Characters like Adam Warlock, Captain Marvel, Shang-Chi, and others often wear suits with similar padding, stitching, and materials, despite originating from vastly different cultural and historical backgrounds across the universe, where each part of the universe has had it's own historical evolution and thus different fashion. By contrast, Fantastic Four appears to carve its own distinct world, with costumes and designs that feel accurate to this alternate history.
Other (in)accuracies
Another form of accuracy is contextual accuracy. This form is concerned with understanding the context in which a story takes place. For instance, the diverse societies in The Rings of Power make sense due to migration, whereas such diversity feels out of place in most of The Wheel of Time. Similarly, characters in medieval or primitive settings looking like they have access to showers and clean clothes daily can break immersion. In House of the Dragon, even though it is fictional, it draws on many architectual styles from realworld history to make it feel contemporary to the world of Westeros.
Similar to contextual and historical accuracy, is linguistic accuracy. This accuracy is the understanding of linguistic development. This is why it can feel off that the kids in Avatar: Way of Water use human words like ''bro'', even though they're speaking an alien language. If the dialogue feels more natural to it's world, is more easy to relate to the characters speaking it. Avatar is also an example of perceived musical accuracy. The music is made to sound tribal and alien, so that the viewer is informed of what they see, even if it's inaccurate to the lore of music within Avatar's universe.
Situational accuracy
These forms of accuracy -where what is seen on-screen is seen as accurate because it limes up with Joe Audience's knowledge- help make sense of the context of the in-universe world. For example, faster-than-light travel in futuristic settings adds a sense of scientific advancement, and crossing vast distances over a long period of time in medieval settings adds a sense of scale, as is seen in Game of Thrones' earlier seasons. Being perceived as (consistently) accurate is important so that the viewer can suspend disbelief long enough to enjoy it.
So, Fantastic Four might not be comic accurate, but it looks to be historically accurate to the world it takes place in. The suit designs reflect what Joe Audience might associate with retrofuturistic 1960s fashion. The same might apply to technology and architecture seen in the movie: it helps Joe Audience understand and accept the historical development, context and situations of the world the story takes place in. Still, comic accuracy is nice too, because Wolverine looked great in Deadpool & Wolverine. Even if it looked like he visited the same tailor as a girl from New Jersey.