It is estimated that 3-10% of the general population have Gilbert’s Syndrome. Males are more frequently affected than females (12.4% and 4.8% respectively). Bilirubin concentration in men is significantly higher, which could be because they have a greater bilirubin load per kilo of their bodies.
One trigger for Gilbert’s Syndrome symptoms may be hormone fluctuations such as those which occur during menopause. I’ve also found that monthly cycles can also trigger symptoms. You can read more about how the liver processes hormones here: https://www.amchara.com/hormones/how-liver-function-affects-hormone-balance#Female%20Hormone%20Metabolism