outgoing internal links contain nofollow attribute
90% come from your WordPress pages and the link generator is not wpForo, it's your profile builder plugin:
Other 10% are member directory pagination links, I cannot provide any support for those, there is no "nofollow" tag in the pagination buttons code, I checked and didn't find, so they are added by some 3rd party JS code or plugins.
I'll let you know if we found any reason. Please do not bump this topic again, this could be my last post if I didn't find any useful information for you.