How do the sniper and marksman rifle bipods work?

Solution 1:

In most cases, the bipod should deploy automatically, but when I use the bipod, it sometimes doesn't deploy properly (I'm assuming it's a bug.)

After several attempts, I was able to confirm that the bipod deploys just like any other underbarrel attachment (such as laser sight, flashlight, GL, Masterkey), by pressing the key to use the attachment.

If you're on console(PS4/5, Xbox), hold down(↓) on your D-pad. If you're on PC, just simply hit X on your keyboard.