A reduction in menstrual flow or duration can be normal in some women, especially if your cycles are still regular (every 21–35 days).
Stress, weight gain ?
Healthy lifestyle, balanced nutrition, and adequate sleep.
I will definitely ask is your normal pattern is normal first
If your cycles remain regular and you have no other symptoms, a lighter period alone is not necessarily a cause for concern.
Next Steps
Hormonal if it’s not regular