These are both 1962 Chevrolet cars.
If you can accept that both these cars can be made in the same year by the same manufacturer, than accepting that Starfleet can make both the Miranda and Walker class within several decades of eachother, isn't that difficult.
But there is no hand of God visually rebooting the universe we live in, so this works. It works because our visual world is reliable.
When we saw DSC Klingons on screen for the first time, we were told this is how they
always looked(for the sake of Discovery and spin-offs, though much was dumped). It was a new visual style for a new visual age. There was no intention for them to look like TNG Klingons one day, we were to accept that this is it from now on. The same way a Walker class would never give rise to a Miranda class.
The thing is, ships from 66-05 were pretty tight. We had seen an Excelsior class on screen with a Defiant class, Defiant on screen with a TOS Constition, TOS Constitution on screen with an NX class, Miranda with an Excelsior, Miranda with a Galaxy class, Galaxy with an Oberth class, Oberth with a refit Constitution. The list can go on and on.
What we aren't going to see is a Malachowski with an Oberth class, or a TOS Constitution with a Shepard class, Pioneer class with a Walker and so on. It's different visual continuities and that's how it's supposed to be.
If any of the above ever happened, I'd be overjoyed. I dislike the visual rift that has occurred between all these shows. Size be dammed, have a SNW Constitution rendezvous with a TOS Constitution and let the fans go nuts.
Maybe the visual canon shouldn't be treated as dogma because it's a tv show and sometimes they make the bird of preys too big and sometimes they give the Yamato a NCC-1305-E because the people making it are only human and trying to make sense of it is impossible unless you're willing to ignore something. Which can be fun! I love tech manuals and stuff, but I don't take them seriously enough that if what's on screen doesn't match up with what was in it or what was in the previous show that it's going to detract from my enjoyment of it.
Mistakes happen, especially with scaling and numbers on screen.
Recent Star Trek has been hinting that it all happened, TOS, Disco and SNW, exactly as it appeared, with no visual reboot. Picard makes it clear that the SNW and TOS Constitution designs both existed, Lower Decks shows that all the uniforms existed, even Section 31 has a classic TOS phaser. Really all SNW has to do now is end with the possibility that the ship could get a refit before TOS and it can connect up.
Actually, you know what, granted. Small efforts have been made, and I appreciate that. Sometimes it feels like superficial fan teases, but if it all connects up in one glorious and messy tapestry, then I'm all for it.