If your genital tissues are atrophying, you have low estrogen (and also often low testosterone as well).
If you are in your mid 50s or beyond, the presence of vaginal atrophy is not telling you anything you don't already know - unless you are on replacement, your estrogen levels will be low.
Whether you choose to treat systemically, locally or not at all is a personal choice.
But when someone in their early 40's or even younger has symptoms of vaginal atrophy, rather than just treating the symptoms this should prompt a clinical assessment as to whether that individual is heading into early menopause. Most guidelines recommend testing FSH in women under 45 and certainly below 40 with symptoms suggestive of ovarian failure, which include GSM.
If endogenous ovarian hormones are going away at this age, this means the individual has potentially many more years ahead of them to live in a hypoestrogenic state, which we know has negative health consequences across multiple organs and systems such as bones heart brain etc, than someone who loses (and doesn't replace) their ovarian hormones at the usual age of menopause or later, which in developed countries is around 51.
This is why it is particularly important at any age but especially the younger you are, to have a holistic assessment with a menopause informed specialist.