In general, when you're going to look at single sales that are this old, you should check how they compare to other sales from that time, especially if your sale induces a very large change:

https://backpack.tf/profiles/76561197964171516#!/compare/1601942400/1602028800 27, less than a month before the sale used here, as an example. There were a lot of sales back then, and only using that very last one is not really representative of the market.

Since it was dumped a few times and has been for sale for less (~30, sales were for 25), I feel that 36 may have been an outlier altogether. It's probably best to wait for the market to restabilize before updating this.