I think how you do it is less important than why you do it
Proportional percentages, shared pot, 50/50 if your salarys are similar are all just variations
What I see on here that can be more of a red flag is:
Person A pays more because they earn more and therefore thinks they are more important in the relationship than Person B and even if they work similar hours expects Person B to have less leisure time because Person A is too important to do household/childcare tasks
Person A earns more but expects Person B to pay 50/50 even on maternity leave and if they go back part time, and expects Person B to do more than 50% of the housework and childcare (why oh why are the 50% bills men never up for 50% housework I wonder)
In both these scenarios and other similar ones it can be really easy if you aren't careful to fall into the trap of thinking someone's value as a person and their amount of leisure time should be based on the amount they earn in a job. Which is likely to impact women with children far more often than anyone else.
Unless someone is lazy or has a terrible work ethic anything other than bills should not be based on salary.
To be fair it can often be that the higher earner works longer hours and therefore to make leisure time equal the lower earner does more household tasks etc
But I also knew someone whose partner insides on 50/50 but wanted a big house and big holidays so she worked hours and hours of overtime to keep up, but then he also expected her to do the vast majority of the housework because she was the lower earner.
so if you are taking about how to deal with money fairly OP make sure you are also talking about how to deal with other things fairly