Reddit throttled its API usage a month before the great 3rd party purge, so I'm guessing whatever collection method that site was using simply doesn't work correctly anymore. Or worse yet, the remnants of the API spits out completely incorrect data itself.
Sounds like Reddit itself has recovered in terms of raw numbers, but I (and others) have noticed yet another downtick in quality. Lot more bots (AI craze doesn't help. And despite the API narrative being used to counter them, they probably suferent the least), comments seem to be as hostile as early pandemic. But these are hard to measure objectively.