The Cerys mod appears to set a allows_productivity flag on some of its technologies. From what I can tell, it doesn't seem to affect productivity modules, but does prevent the research prod technology from applying when researching the tech in question. From what I could tell, when a tech with this flag set is at the front of the queue, it sets the productivity of each lab to only reflect their modules. I think this mod would them apply the resulting productivity modifier across the queue rather than just for the specific tech. Alternatively, if the tech in question is not at the front of the queue, the flag wouldn't take effect and would get researched with the full research prod tech modifier.
This wasn't a huge issue in my game since I haven't automated promethium science, but it is a discrepancy between intended behavior and actual behavior. It also could be difficult to fix since entity.productivity_bonus already tries to account for this, but doesn't account for the possibility of multiple techs being researched at once.
