A couple of references

In the HERO study, relugolix demonstrated sustained testosterone suppression superior to that of leuprolide acetate (97% vs 89%; difference 7.9% [95% confidence interval, 4.1–12%; p < 0.001]).

Men (N = 934) were randomized (2:1) to receive relugolix 120 mg orally daily or leuprolide acetate injections every 12 wk for 48 wk.

Overall, 74 of the 137 men in the relugolix cohort recovered to testosterone >280 ng/dl, with a median time to recovery of 86.0 d (95% CI, 65.0–92.0), versus two of the 47 men in the leuprolide cohort, with a median time to recovery of 112.0 d
https://www.sciencedirect.com/science/article/pii/S2588931123002900
Examples of the relationship of the duration of ADT exposure to subsequent recovery to their
original T levels after stopping ADT are as follows:
- After 3 - 9 months of ADT nearly all men fully recover by about 10 months;
- After 18 - 24 months of ADT only 60% fully recover by about 3 years; and
- After 36 months of ADT exposure only 50% fully recover by ~ 5 years.
It is clear that after receiving ADT for longer than 6-9 months many men never fully return to their
T baseline. This raises the very important question of whether it is safe to offer replacement
testosterone in symptomatic men who have been rendered persistently hypogonadal (<230
ng/dL).