Previous weapon

`Mouse wheel down`

All hotkeys for Call of Duty: Black Ops 4

Interface Navigate up	`W`
Interface Navigate left	`A`
Interface Navigate down	`S`
Interface Navigate right	`D`
On foot Fire	`Mouse left click`
On foot (hold) Aim down sights	`Mouse right click`
Interface Remove / unbind	`R`
On foot Next weapon	`Mouse wheel up`
On foot Previous weapon	`Mouse wheel down`
On foot Switch to primary weapon	`1`
On foot Switch to secondary weapon	`2`
On foot Equipment	`E`
On foot Health kit	`X`
Interface Navigate to previous tab	`Q`
On foot Interact	`F`
Interface Confirm	`Space`
Vehicles & Scorestreaks Fly down	`C`
On foot Prone (toggle)	`Left Ctrl`
Vehicles & Scorestreaks Boost	`↑ Left Shift`
Vehicles & Scorestreaks Handbrake	`V`
Vehicles & Scorestreaks Switch control mode	`Mouse middle click`
On foot Autorun	`H`
Vehicles & Scorestreaks Next seat	`Z`
Game mode specific Change to class 1	`Num 1`
Game mode specific Change to class 2	`Num 2`
Game mode specific Change to class 3	`Num 3`
Game mode specific Change to class 6	`Num 4`
Game mode specific Change to class 5	`Num 5`
Game mode specific Pick up attachments	`G`
Game mode specific Scorestreak slot 1	`3`
Game mode specific Scorestreak slot 4	`4`
Game mode specific Scorestreak slot 5	`5`
Game mode specific Scorestreak slot 6	`6`
Interface (Hold) Inventory	`⭾ Tab`
Interface (toggle) Map	`M`
Interface Text chat	`⤶ Enter`
Interface Text chat	`num⤶ Enter`
Interface Text chat (match)	`T`
Interface Text chat (team)	`Y`
Interface Text chat (party)	`P`
Interface Voice chat (push to talk)	`B`
Interface Screenshot	`Print Screen`
Interface Open friends menu	`F1`
Interface Open social menu	`O`
Interface Open social menu	`F2`
Interface Open settings menu	`F3`
Interface Open player account menu	`F4`
Interface Accept party invite	`F7`
Interface Dismiss party invite	`F8`
Interface Navigate up	`↑`
Interface Navigate down	`↓`
Interface Navigate left	`←`
Interface Navigate right	`→`
Interface Navigate to previous tab	mousebutton4
Interface Navigate to next tab	mousebutton5