Solar geoengineering is the hobbyhorse I usually use as an example of this. It's an open secret (see e.g. https://www.nature.com/articles/d41586-021-01243-0) that most scientists in the field won't research it, partly due to safety concerns but partly because they think that decarbonization is the right policy and they don't want to risk "detracting from efforts to rein in greenhouse-gas emissions". Maybe that's the right judgment, but it's hardly free from motivation and agenda.