I haven't watched most of Picard yet except the first few episodes of season 1, but I weirdly picked up this detail from the IDW Picard's Academy comic. I enjoyed it. Maybe not a masterpiece, but it was at my local library and I would read it again just to look at Spock's outfit:
There's just something weirdly fitting about business casual out Starfleet Academy Instructor Spock.
Jokes aside, I would view this more as a Thomas Riker situation - Voyager was split in two in that moment. Both Kims were the same Kim before the divergence field, so both Kims have the same record before then.
In truth, probably part of Kim being stuck at one rank was probably because of a lack of transfers from Voyager, for obvious reasons - it's practically raining promotions on the Cerritos for instance, and transfer seems relatively frequent in Lower Decks.
Maybe from 2371-2378, while Tom Paris was busy being his Delta Quadrant counterpart.
Like, I don't hate Tom Paris (at least late VOY, anyway), but you can't deny that in combination with his early personality, that face just looks inherently punchable for some reason.
Indeed, it was, followed by Ten Forward and This Might Be Lemmy.