There are definitely lines to be crossed. Let me tell you about one of them.
There is a comics creator named Kieth Giffen. He's done a lot of solid work over the years for DC and Marvel, there's a playful love of the medium and its history that flows through a lot of his work. At first his style was pretty middling; nothing terrible, nothing to really stand out from the pack. Then one day his work changed dramatically - he got a lot more daring in spotting his blacks, inking with a heavier brush, and doing a lot of panels that were a closeup of a backlit head with rim lighting, and eyes and teeth standing out in white. It was grounded in observation but had a lot of fresh ways to abstract a scene in the service of story. It was like nothing else on the racks and really striking.
It was also completely swiped from the work of an Argentinian artist named José Muñoz. Pick up one of Muñoz's shadow-drenched crime stories, put it next to one of Giffen's superhero tales, and you could clearly see the influence. And not just the influence, influence is okay - Giffen had started entirely cloning Muñoz's style, completely dropping all his other influences in the process. Muñoz was not happy when he heard about this, and neither were other artists in the field of comics. Influence is one thing, everyone's influenced by other artists, and if you're familiar with an artist's influences you can tell. But dropping all your other influences to start drawing almost exactly like a new one? That's just not done.
Giffen got a lot of shit for this. Giffen quit comics for a couple of years after this, and when he came back he had a new look. He still does the Shadowy Muñoz Face now and then but it's more along the lines of one of the many things he's borrowed from his multiple influences rather than one of the ways he was wholesale ripping off Muñoz.
"Style theft" is completely legal in the eyes of the court. There was nothing legally actionable going on here. But in the court of his fellow artists, Giffen was judged, and found guilty.
There's a range here. Nobody's going to care if you pick up a collection of Winsdor McCay's pioneering 19xx comic strip "Little Nemo" and do a dream-themed story that borrows his distinctive panel composition, lettering, and inking choices. Nobody's going to care if you do one drawing that precisely lifts Mike Mignola's heavy use of black and thin, clear lines. If you do superheros long enough then you're pretty much obligated to do at least one story that emulates Jack Kirby as closely as you can. If you worked as someone's assistant for a half a decade then you are very much allowed to bust out a perfect rendition of their style at any point in your entire life. But there is definitely a line you can cross where every artist (and a lot of non-artists) who sees a side-by-side view of what you're doing and what you're swiping from will say "dude, not cool, stop swiping their style".
These image generators actively encourage adding the names of prominent, living artists to your prompts to get the results you want. Is this crossing the same line Kieth Giffen did?