Great analysis, @pfm!
As you stated, price hiking happens when supply is limited and FOMO kicks in. Additional supply (a latency period of about 3 weeks in this case) kills the trend with undercutting.
A similar point was raised by AlphaHoarder on YouTube when he attempted a large buyout of old MTG cards. Originally, the price hiked quite a lot. But after the large stores and “investors” saw this movement, they unloaded their heavy bags and drove the price right back down to normal levels.
If you look at the sales data by day of the week, Saturday and Sunday sales almost always drove the price for the following week. This is because auction houses (large eBay sellers, PWCC) ended their auctions on the weekend, often selling multiple copies of the card. This large supply (i.e., in November and December) allowed the price to return quickly to its destined floor.