I've bought and sold a lot on Reverb since I joined in Fall 2019 (over 100 transactions) and right now is probably the slowest sales have been. I think people just have other priorities for their money right now since Covid restrictions have all been lifted. Also, prices have climbed to astronomical heights: Vintage gear that was previously undesirable (e.g., 70's Gibsons) has more than doubled in value and a lot of used gear is selling for 90% of new.
That all said, while sales have slowed and will probably continue to slow for some time, I don't see prices coming down drastically. Sure, new-ish guitars from the last 10 years or so will probably drop but I think the vintage market has been permanently altered. If you're buying a 70's or 80's Les Paul right now for $5000+ or an 80's JCM 800 for $3000, there's no way you're just going to take $1500. Sure, there might be a slight reduction, maybe, but I thinkin the collective zeitgeist no one wants to lose money and so these prices will hold. The Pre-Covid days of 70's Les Pauls that were $1800 and JCM 800's that were $1200 are over and I don't think those prices will ever be back.