Explosions force burrowers to un-burrow, including plasma explosions and stuns (although I've had mixed successes with the latter).
The burrower warriors (= the red bugs) have medium armor (or pen3) on their faces, I don't remember if the Helldivers Mobilize warbond has a pen3 primary but if it does, try that one; otherwise, you can use the MG or the HMG, among other support weapons.
Other than that, it depends on the warbonds you've got so far; what have you got so far?