In terms of "hard" onscreen facts, there's no particular reason to think that the entire universe underwent a significant change between TOS and TMP. All we really saw change was the Enterprise
. And naturally a near-total modernization (from the technological angle) would invite the total
total modernization (for sheer aesthetics, or PR purposes, whatever you call it) of insignificant details from intercom buttons to onboard cutlery - there would be no reason to leave something like that un
changed when the very point is to introduce a new thing.
For all we know, Starfleet HQ had looked like that for the past twenty years or so, and it just so happened that the hero ship in TOS was ten years behind the times, and the hero ship in TMP was built (and decorated) to be ten years ahead of them.
On the other hand, "hard" onscreen facts include Voyager 6 being more than three centuries old. That pushes TMP to 2278 at least, considering Voyagers 1 and 2 date back to 1977, and forces an eight-year gap between TOS and the movie. Unless we assume the Voyager program of Star Trek was different from the real one in some details.