Maybe you could put it back to the detractors, if they feel red buttons and "less effective" perhaps ask them why they feel that? what have they seen/read which has given them that opinion?
Try to understand where they are coming from with an open mind and see if any of their reasons are worth spending time investigating.
It sounds like you do actually have A/B type data in terms of your conversation vs industry standards and this for me is your justification (as well as the opportunity cost of making a change to something which is working).
I would suspect they likely have no data, meaning it's just an opinion thing. Often in Western culture people associate red by default with a negative action semantically, but when you look at colour psychology, red can be construed as energetic and exciting - https://www.verywellmind.com/the-color-psychology-of-red-2795821 which may suit your product.
Additionally, the meaning of red in Eastern culture is very different
Red is a popular color in Chinese culture, symbolizing luck, joy, and happiness. It also represents celebration, vitality, and fertility in traditional Chinese color symbolism
Who is your user base? How might any of those points apply or not.
Ask them to put the data where their mouth is! especially if they are expecting your to defend your existing position!