Sale 1:

https://backpack.tf/profiles/76561198125894529#!/compare/1592611200/1592697600

https://backpack.tf/profiles/76561198073500295#!/compare/1592524800/1592611200

Sold with DP Gonzilla for Mallard Oiled

use there

sale 2:

https://backpack.tf/profiles/76561198073500295#!/compare/1592611200/1592697600

https://backpack.tf/profiles/76561198048851745#!/compare/1592697600/1592611200

QS

sale 3:

https://backpack.tf/profiles/76561198048851745#!/compare/1592697600/1592784000

https://backpack.tf/profiles/76561198290723276#!/compare/1592697600/1592784000

Sold for ~10 keys

sale 4:

https://backpack.tf/profiles/76561198229066336#!/compare/1592006400/1592265600

https://backpack.tf/profiles/76561198341171690#!/compare/1592179200/1592265600

QS

sale 5:

https://backpack.tf/profiles/76561198365053592#!/compare/1591660800/1592870400

https://backpack.tf/profiles/76561198050518375#!/compare/1592352000/1592438400

Untrace

sale 6:

https://backpack.tf/profiles/76561198050518375#!/compare/1592438400/1592524800

https://backpack.tf/profiles/76561198002757046#!/compare/1592352000/1592438400

QS

sale 7:

https://backpack.tf/profiles/76561198089247727#!/compare/1592524800/1592611200

https://backpack.tf/profiles/76561198198970178#!/compare/1592438400/1592524800

Sold for Miami Pampered

Pampered Mini:

https://backpack.tf/suggestion/5f23852f34aa831f9325a1d2

Suggestion for 10.5 keys

sale 8:

https://backpack.tf/profiles/76561198198970178#!/compare/1592524800/1592611200

https://backpack.tf/profiles/76561198144811618#!/compare/1592611200/1592697600

Sold for ~11 keys (1 key bought using ref)

sale 9:

https://backpack.tf/profiles/76561198144811618#!/compare/1592611200/1592697600

https://backpack.tf/profiles/76561198341171690#!/compare/1592611200/1592697600

QS soon after Sale 8

sale 10:

https://marketplace.tf/items/tf2/30479;5;u6

https://backpack.tf/item/3034670316

$21.99 / $1.98 = 11.11 keys

Total sales @:

10, 10.5, 11, 11 keys

buyers up to ~9 keys,

2 high buyers for ~10 keys, excluding as multiple non-universal buyers below that.

Taking 10 - 11 keys.