Your account is configured to only count purchases that happen within 24 hours of a click. That's reasonable for impulse-buy products. For skincare, where someone typically thinks about a $40-80 purchase for 3-5 days, that setting hides most of your real conversions.
Meta still sees those purchases happening — but your dashboard doesn't. Switching to 7-day click is one settings change and your reported ROAS typically jumps 8-15% with no other action.