Eight month old price.

Sale 1:

https://backpack.tf/item/9111929915

https://backpack.tf/profiles/76561198127045035#!/compare/1603497600/1603411200

https://backpack.tf/profiles/76561198345436872#!/compare/1603497600/1603411200

Used in bulk for Searing Plasma Patriot Peak.

Sale 2:

https://backpack.tf/item/9111929915

https://backpack.tf/profiles/76561198345436872#!/compare/1603497600/1603584000

https://backpack.tf/profiles/76561198038984127#!/compare/1603411200/1603584000

1:1 for Arcane Assistance Taunt: Pool Party???

Definitely too low: https://gyazo.com/a9c65138e0223b36df983d2367207ca9

Quick (not in-depth mini) for Arcane Assistance Taunt: Pool Party:

https://mannco.store/item/24982

https://mannco.store/item/1 (key price)

18.53/1.61 = 11.51, rounded to 12 keys.

Sale 3:

https://backpack.tf/item/6462222215

https://backpack.tf/profiles/76561198221421520#!/compare/1607817600/1609200000

https://backpack.tf/profiles/76561198041513103#!/compare/1609113600/1609200000

This + 44 keys for Verdant Vortex Patriot Peak.

Sale 4:

https://marketplace.tf/items/tf2/30743;5;u57

October 21, 2020: $79.99

$79.99 / $1.86 = 43.01 keys (https://manic.tf/keyprice/?at=2020-10-21)

Conclusion:

Using the only valid sale, which is the MPTF one.