https://www.tandfonline.com/doi/abs/10.1080/19419891003634430

Did you chose that paper on the basis of the title, without reading it? Nice one.

For those who actually do want to read the paper, you can access it here. Some notable features:

• The study was performed in the US in 2009, before so-called "gender affirming care" was mainstream. It is highly unlikely any of the subjects had received gender affirming care.
• The study did not ask participants whether they had gender dysphoria.
• Nor did it ask whether they had received any sort of treatment for such dysphoria.
• And it certainly did not ask whether the suicide attempts occurred before or after any such treatment.

Since the study does not look at gender-affirming care at all, it cannot support your contention that gender affirming care reduces suicide attempts.

In addition, the study is not a good match for transitioning teens today, who are mostly girls transitioning to male:

• The study is overwhelmingly made up of straight or bisexual white males who identify as women (78% are bisexual or heterosexual natal males; 58% are natal males who identify as "female", "somewhat female", or "equally both").
• The study proclaims itself as having subjects from multiple ethnic backgrounds, but just 5 out of 153 subjects are non-Caucasian.
• More of the subjects identify as "cis" than of non-Caucasian ethnicity (6% of the natal males identify as exclusively male, and 7% of the natal females as exclusively female, making at least 9 individuals; if we include those who identify as "somewhat" their natal sex, that increases to 40 individuals).
• The study involved only subjects over 18, not teens, with an average age of 47.

Regardless of the strengths or weaknesses of the study, it is completely irrelevant to the question of whether or not gender-affirming care reduces suicide amongst trans people.