During COVID there was a lot of people that just needed something to do to entertain themselves and keep busy. Some people who were already in the hobby probably indulged even further during these times, and some people maybe got started reefing to pick up a new hobby.
And economic factors almost certainly play a part. When rent/housing is costing more than ever, grocery prices going up and up, etc., people are being more selective with how they use their expendable income (if any).
That said, I still see reasonably priced gear and frags sell (and rather quickly). And I think that the over commoditization of coral has led to some burnout. It is increasingly common to see people who buy over priced corals with the mindset of “I can sell frags of this for so much.” And the growing number of posts over the years (on many different sites) showing a chopped up, booger sized frag accompanied by a silly price tag and a “no lowballs, I know what I got” in the listing is honestly pretty tiring.
Been reefing for many years, and things tend to gently correct over time.