PUP.Optional.Wajam is the detection name for Wajam, a browser add-on marketed as a “social search.”
This is the generic detection for programs that use system resources to earn payments in digital currencies. Since it is difficult to determine if they are installed by the system user or by a threat actor who receives the payments, Malwarebytes alerts you about their presence.
Malwearebytes can remove these miners without further user interaction. Full removal may require a reboot, and Malwarebytes will prompt you to do so if necessary.
Should users wish to keep it, they can add the detections to the exclusions list. Here’s how to do it.