References other Star Trek shows. Some say it's not "real Star Trek" because they "never" reference something from TOS or Enterprise, but they *always* reference TOS or Enterprise or TNG or whatever. They devoted an entire episode to following up The Cage. They had Harry Mudd show up as a recurring antagonist. They made a sequel to In a Mirror, Darkly.
They can't help themselves. It's just what they do. Star Trek: Picard will take care of some dangling 24th century threads, Lower Decks will probably have some sort of tongue-in-cheek nods to everything, and Discovery 3 will do some nod, however slight, to the known temporal shenanigans of the era.