Spider-Gwen. Before now, Gwen hasn't been known for these abilities, but her awareness that she's in a comic book is growing, and there may be some hints that she was taught this by Deadpool himself.
In TVA (2024) #1 by creative team Katharyn Blair, Pere Pérez, Guru-eFX, and Joe Sabino, Ghost-Spider has been recruited by the TVA to help launch the "new and improved TVA", as she's hiding out in the TVA after an incident on her home timeline until they find a way to deal with her.
While Gwen is walking the halls of the TVA, she discusses the plot of the Loki Disney+ series when she says, "I don't have the page count to go into it all." It's a surprise fourth-wall break that sets up a new trait to go with Gwen's new status quo. It's also clearly not a one-off, as Gwen begins the issue asking for the reader's thoughts on her new holster.

Marvel's Comic Continuity Has Found a True Bridge With the MCU, And We Have the TVA to Thank
Marvel's new "TVA" comic series is a concrete link to the MCU, suggesting a greater degree of connectivity in Marvel's vast multimedia Multiverse.
Spider-Gwen Marks Her TVA Debut by Breaking the Fourth Wall
Gwen's New Ability Could Have Been Taught to Her by a Fellow TVA Variant
Per her new starring role in TVA, Spider-Gwen knows she's in a comic book. Medium awareness is not an ability Gwen has displayed until now, but it doesn't seem unusual for her character. If it becomes one of Gwen's new abilities outside TVA, it would make her one of the few spider-totems that can break the fourth wall, ing Spider-Ham, and other fourth wall breakers like Deadpool and She-Hulk. There are a few explanations for her new ability, including learning it from a variant of Deadpool in the TVA.
While Ghost-Spider is walking the halls of the TVA, she es a framed photo of Deadpool. This could be any variant of Deadpool from across the multiverse, but a very famous variant of the Merc with a Mouth recently made an appearance at the TVA in the MCU's Deadpool and Wolverine film. Time works weirdly in the TVA, but if this variant of Deadpool ran into Gwen during his time at the TVA, or during his return in the post-credit scene, he most definitely could have taught her his medium awareness. It's for sure something Deadpool would do, and it's actually how he got the ability himself, with Loki informing him, "There is a man with a typewriter."
Ghost-Spider is Now Connected to the Infinite Marvel Multiverse Via the TVA
A Surprising Movie/Comic Connection Is Now in Effect
Another explanation for Ghost-Spider's new abilities could just be her newfound connection to the infinite timelines of the Marvel Multiverse. Gwen has always been connected to the multiverse, frequently traveling between realities with her 'Ticket to the Multiverse' gadget, but the TVA offers next-level access to notable worlds. Since Loki destroyed the temporal loom and freed the multiverse in Loki, the TVA watches all the timelines, including live-action, animated, and comic books. That's a significant difference to Spider-Gwen being able to access largely similar comic realities, and this increased scope could have introduced her medium awareness as a side-effect.
While Spider-Gwen hasn't demonstrated much medium awareness before now, it's not exactly the kind of thing a character can forget, suggesting it's a power that's here to stay. It will be interesting to see how TVA continues to develop this new trait, and how it influences Spider-Gwen's understanding of the Marvel multiverse and her place in it. For now, it's fun enough that Spider-Gwen is now a Marvel hero who can make fourth wall-breaking quips - one of the things fans have always loved about Deadpool.
TVA #1 is available now from Marvel Comics.

Deadpool
The merc with the mouth first appeared in an issue of New Mutants in 1990, and since then has gone on to get his own series and a massive cult following. With his incredible powers of healing and regeneration, Deadpool was initially depicted as an X-Men villain but went on to become an anti-hero. After getting his own movie series starting in 2016, the third Deadpool movie finally brings the wisecracking, fourth-wall-breaking character into the Marvel Cinematic Universe.