Basically what jubsz said, he briefly hit every point I would say. It's not just 4runners by any means, look at practically any 4x4 and they're all following a similar trend, some worse than us - like XJs. The Doug DeMuro Tax hit them hard
Hell most cars are going for way more than they should. JDM market is f*cked beyond belief and has been for a while. I think the pandemic contributed greatly to it through a lot of different ways, but even ignoring the elephant in the room it seems like many people are realizing that it's much more cost efficient to upkeep a car than buy a new one at 150k. But the problem is many cars have largely been crap for the past 10-15 years, at least in one way shape or form, and cars before that get more and more scarce every year. Similarly many find they look better and are much more versatile - lots of people don't like things often forced upon us; like unibody designs, ultra low ground clearance, super tight fenders that don't allow for bigger tires, those dumb giant grilles, etc. While some of these are regulation induced and some are purely driven by style, many younger people regardless find it inferior to options we had previously (and rightfully so I dare say.) Not many people 20-30 years old wants some crossover CVT bullshit.
Also with the UN twisting everybody's arm to go ditch gasoline powered cars I think that has a good portion of individuals worried about future options and would rather stick with what they have - but like you said that's a different topic for a different board