I was curious and a bit skeptical that sex change operations materially affected suicide rates for trans people but available papers tended to find significant effect sizes of about 50% reduction
The data is poor quality. It's not like you can randomize who gets a sex change operation. And there are major issues with even knowing who to count when people can just decide they're not trans any more. All the research on this is riven with such unhandled problems.
The research is also highly motivated. A researcher who found that sex change operations were harmful would be targeted for endless harassment by gender activists, if they could get published at all.
Did that study account for the socioeconomic status of the participants? Common sense suggests that people who can afford to undergo such surgeries would tend to be richer, more supported, and from better neighborhoods.