Lean / fat % drastically off

[Debcg]

I am a pretty fit female who works out with weights regularly. 5'4" 134 lbs, size 2 for reference. I use the "lean mode" as well and the aria scale tells me my body fat is 30%. If I don't change anything but the setting to be a male instead of a  female my fat drops to 18%🤔. I think this scale is biased to women.

[LZeeW]

Hello @Debcg and welcome to the Community.  The technology that fitness scales use to estimate percent body fat is notoriously inaccurate.  This is true across brands and isn't limited to Fitbit scales.  I firmly believe that users shouldn't focus on the exact number, but follow trends.  Have you ever looked at any of the sites that show images of women at known body fat?  Here is one of several.  You might find it more reassuring. 

With respect to you comment about bias, I absolutely expect the scale to report a very different body fat percent if you change your sex to male.  Basic human physiology will tell you that a male and female of equal height and weight will have different body fat percentages.