Maybe not entirely a bug, but doesn't feel right.
The wealth cost of research is tied to research rate, which makes sense originally. Better research tech, means more expensive labs.
But it breaks a bit if you change the global research rate. Since this effects the research rate of labs, you end up with really cheap labs.
Sure, you presumably pay the same amount of wealth pr research point, but once your industry gets going, wealth is the real limiter on research. So you can end up with the same amount of research, you just need to spend the minerals/time to build more labs. Which kind of removes the point of the global setting after a while.