Here's a great list of all the times that ST Discovery broke canon.
https://screenrant.com/star-trek-discovery-broke-canon-facts-trivia/
Number 15 is wrong as we see a mutiny or two in TOS it's self. I guess Spock forgot, which is amazing since he was the central figure in the mutinies.
Number 14 is disproved by it's own information.
Number 13 is also not a canon violation. Adding a relative to a characters backstory only violates continuity if continuity has previously established the relative doesn't exist. Spock's notorious for relatives popping up out of the blue: Sarek, Amanda and Sybok. Even Saavik to some extent.
Number 12. Has this writer ever seen a Klingon or watched Star Trek? Klingon honor is a joke. The make works with how the Klingon look has evolved since TMP. The baldness is the only radical departure.
Number 11 We see one type of Starfleet ship in TOS. but I doubt that's the only starship design in the entire fleet. By the movies we see addition designs. So no, the Connies aren't the only "starships" out there.
Number 10 Nope, We see the insigna on non-Enterprise personnel in TOS. The other insignia were a production error.
Number 09. We don't know anything about PIke's career outside the Cage/Menagerie. So who knows what things he's done. The writer's really grasping to hit the magic 15.
Number 08. No it's not been "said time and again that the Klingons didn’t acquire cloaking technology until after the Romulans." At least not by anyone writing the show.
Number 07. Nope. Kirk and Spock are well aware of Organia at the start of "Errand of Mercy". What they don't know is the Organians are godlike non-corporeal beings.
Number 06. Is the tribble alive? I don't recall it moving.
Number 05. More grasping at straws. Why is this so high on the list?
Number 04. Yeah, I think Stamets and Lorca know they did a "bad thing". No really a canon violation. One of the reason we know about the ban is from characters defying the ban.
Number 03. Haha, They even mention the holodeck in all but name from TAS. It's pretty obvious the DISCO version is not the "can't be distinguished from reality type" introduced in TNG.
Number 02. Another grasp. The Andorians and the Tellerites are barely present in TOS-VOY, why is this an issue?
Number 01. The Spore Drive. As discussed ad nauseam here and probably elsewhere, it's another in a long list of tech buried and forgotten in Star Trek. The whole "never mention in future shows" is disingenuous. Well duh, it's being written decades later!