Even sugar-free drinks are suspected to increase your chance of diabetes, obesity, and a wide variety of other health issues. High consumption of artifically sweetened beverages are suspected to increase your likelihood of gallbladder and biliary tract cancer, notably a large increase in cholecystectomies, which you say you’ve had.

Here’s a long review of smaller-scale studies of a variety of associations and/or suspected causations of diet soda consumption - Notably arterial disease and “remodelling”, Weight gain, Depression in later life, Eating disorders, impaired cognitive development, hip fractures, UTIs, Diabetic retinopathy, End-stage renal disease, Leukemia and lymphoma, and overall mortality. The review concluded that by objective standards, the included studies were all at least of “moderate” quality.

Need I go on?

Is a lot of that going to be correlative? For sure yeah. Is it still maybe a very good idea to incorporate more water into your diet? Also yeah.