Due to new information, Splatoon 3 imagines a different reality in which ocean creatures, rather than mammals, took over the landscape. The game's main character, an Inkling, can take on both the form of a kid and a squid.
The Splatoon series is primarily known for being a competitive online shooter, but the developers manage to infuse in extensive lore around the day-to-day activities. This is done by having a pretty solid single-player campaign with a story, as well as by giving players the opportunity to discover collectibles, like scrolls, that reveal more about the games world.
Lil Judd is a cat character introduced in Splatoon 2. He is well-known for being apprehensive about being second to Judd. In Splatoon 3, you can collect a Sunken Scroll that appears to depict the process of cloning Lil Judd. His fur is a nicer brown, his eyes are wider, and he is smaller than Judd.
[Ed. note: This post contains spoilers for the final boss of the single-player campaign of Splatoon 3.]
Lil Judds' character model undergoes a strange transformation after beating the single-player campaign of Splatoon 3. He starts wearing a headset, and this tiny detail might be crucial in identifying his potentially criminal intentions.
Salmon Run is a game mode played by players who take on a shady temp job for Grizzco Industries in order to collect valuable power eggs. At the end of Splatoon 3, we meet Mr. Grizz, a giant grizzly bear named Mr. Grizz who wants to devastate the area with mammals. Turns out he is the big baddie of this game.
After you beat Mr. Grizz, all indications indicate that the big boss will be annihilated. However, Grizzco Industries is still alive and well after you beat the solo campaign. This leads to a question: Who is running Grizzco and talking to you through the headset? Now fans think it is Lil Judd, who wears the headset after you beat Mr. Grizz.
Given Lil Judd's general demeanor, it would all make sense. In Splatoon 3, the opposing team is always shown to you as being the Bad Guys, and Lil Judd always represents them. Also, he is a mammals, so it makes sense that he does not dislike Mr. Grizz.
There are a few flaws in the case against Lil Judd. Grizzs voice is the predominant one at the end of the game, and his garbled voice changes during the post-solo campaign. So it's possible that there's just a minor inconsistency between the story and match mode. But we'll just have to wait for a new Splatoon game or DLC to see if this particular plot line gets addressed further.