Star Trek: Discovery updated that era of Star Trek (10 years before Kirk) to look not so.....1960's. Which is fine. I get it. It would've been silly to force Star Trek: Discovery to make everything look like how it did in TOS. That's all well and good. It presents a problem, however. In the TNG episode "Relics" we see a holodeck simulation of the bridge of the original Enterprise straight outta TOS. They didn't update the design whatsoever. They just recreated it perfectly. In the DS9 episode "Trials and Tribble-ations" when the DS9 crew travel back in time to the TOS episode "The Trouble With Tribbles" they, once again, didn't update the TOS look at all. They kept everything the exact same way it looked back in the 1960's. And then in the Enterprise two-parter "In a Mirror Darkly" we see the USS Defiant from TOS end up in the Mirror Universe with, you guessed it, everything in that ship keeping the same exact aesthetic from TOS. Having said that, how can said episodes be canon anymore since they contradict what we've seen in Discovery? Thanks to Discovery, the aesthetic from the 1960's TOS is no longer canon and thus the episodes I mentioned can't be canon anymore.