Legacy extensions
Has Malwarebytes released an update which takes care of this problem?
iMac 21.5″ 4K, macOS 10.15
Question marked as
It isn't a "problem."
When Apple releases the next major OS (10.16), those extensions will not work anymore. At that point, it might be a problem, but since that particular extension serves no purpose on macOS, there is no need to worry about it.