I'm ganna go with Caitsith and the Overly Sarcastic Productions' Red on the definition, or at least when it becomes problematic.
Ridiculously overpowered charecters are a dime a dozen. John Whick, Superman, Master Chief, Stealth Archer build of Dragonborn, exct. exct.
Those with nigh invulnerable plot armor as well. James Bond, Conan the Barbarian, Wiley Coyote, eect..
Or are just too perfect.
MCU Captain America, Jesus Christ, Fropy.
Even self inserts can be great. Nabeshin, Hermony Granger, J. Jonnah Jamison.
The sue at its core revolves around the character being the most awesome thing since ever as its start and end point and does little if anything to expand to anything more meaningful than that.
As is, just going off Watch Mojo, we don't have that problem. Over powered with the force, well that seems par from the course with Yoda's race, and even then the kid only has limited use of it it before passing out. He can heal, force choke, move objects and so on, but stopping the rhino took alot out of him in the same way of Conosuba's Megemi gets whiped out when she does explotion magic.
He's curiosu about things and acts just how a cat or toddler would act (or better yet, a combination of the two).
He also shows signs of fear, joy, confusion, embarisment, and now I'm coppying daddy moments.
If anything is a sue in starwars, its probably BB-8 and even then I will defend my soccer ball of doom till the end of of the internet.