A lot of fandom menace types have spent years insisting that particular details about Discovery mean that unbeknownst to CBS and the creators themselves, the series was somehow "really" in an alternate timeline. That's not how fiction works, and those guys were never right and never will be.
Ordinarily, no matter how big a difference between two shows' treatment of the same events, all we can really say is that one represented it this way and another represented it that way. I mean, if this wasn't a franchise with time travel and parallel universes, then the same inconsistencies would invite different excuses from a similar line of fan. I don't find those kind of excuses compelling.
However, "Tomorrow and Tomorrow and Tomorrow" this season pretty explicitly identified something as having changed due to time travel nonsense, where the original timeline was the history known in TOS, and the altered one was the past of SNW. IMO, that did awkwardly leave a door open.
Of course, in that case, it's only the date of the Eugenics War that's been delayed by 30 years and counting, since it hasn't happened yet in the real world, and so that Trek can keep making cultural references beyond 1992. After Boimler showed up on SNW Enterprise bridge and didn't make a comment about how it seemed bigger in real life, which seems like the most natural occasion in the world for that to come up if it was going to, I don't imagine they'll ever call much attention to canonicity of set design.
Maybe it's splitting hairs to say that technically there's a timeline difference that doesn't matter. It's obviously not why the sets look different, at least until someone decides it is, and it's nothing related or similar to the Kelvin timeline. And technically, the SNW episode was very explicit that these changes were altering the timeline, not splitting it, so if your TOS BD collection hasn't vanished, the changes must not have been very important.