When the very idea of another pre-Kirk show was even mooted there was a very clear statement that it would not interfere with the existing canon.
13 episodes later we have;
And this is before we get into all the nonsense of the badges/uniforms/ships/effects etc. which all clearly post-date ST:TNG, and don't even work if you assume this is the Kelvin timeline.
13 episodes later we have;
- Spock's adopted sibling, never before referenced.
- Magical intra-universe teleportation drive (it's ok, we will destroy a key component of its operation in ep 12. Oh wait, grew replacements in ep13).
- A Klingon war that all but wipes out the Federation.
- A Starfleet which lies to its crew members before intentionally attacking the Klingon homeworld under a Mirror Universe Captain.
And this is before we get into all the nonsense of the badges/uniforms/ships/effects etc. which all clearly post-date ST:TNG, and don't even work if you assume this is the Kelvin timeline.