This reminds me of the arguments around wrestling TV ratings, both in the late '90s and in the past couple years. People with a tenuous grasp on statistics, human behavior, or the completeness of their data nonetheless trying to read the tea leaves and blaming basically anything that they don't like.

We're most certainly in a lull, that's obvious and incontestable. No way to know the magnitude accurately. It's probably sharper than previous ones, but Endwalker as a whole represented a somewhat unprecedented population surge, and we don't have any good analytic data on what that shift meant in terms of population segments, which means there's no real good way to accurately map out where the decline is coming from. Hardcores dropping off without content? Casuals finally wrapping up their four expansions worth of MSQ and dropping off? Something in between?

We can look at a couple interesting tea leaves of our own to look for trends that don't fit the argument - and upon evaluation of the number of Anabaseios parses uploaded in 6.4, it certainly doesn't appear to be significantly far behind the totals for Asphodelos in 6.0 or Abyssos in 6.2. Account for the fact that we're still in the middle of the 6.4 cycle and the rate of uploads, and the small gap that exists seems very likely to close in the coming weeks. This is kind of a surprise to me, actually - I really didn't expect the numbers to be as close as they are. To see basically zero observable decline in what is generally considered the flightiest segment ("clear the tier and unsub") raises some interesting questions about the prevailing narratives.

(As an aside: one could certainly argue that stagnancy in this case is an effective deficit since you should expect those numbers to be growing over time as people 'graduate' into the endgame, but when we're talking about 'lost players' that discussion feels like a bit of a tangent.)