They are highly inaccurate because they rely on hydration levels.
If the "number" is important to you then you'll have to go pay for a hydrostatic weighing or dexa scan. Both of those are considered the gold standard but still - not 100% accurate.
I'll admit I was obsessed with body fat percentage for a while and even had myself hydrostatically weighed but now I think it's not relevant because what matters after health is how you feel about how you look, not the "number".
"Getting solid information is easier than ever. Getting misinformation is even easier." - Kaplods
Maintaining for two years and I eat whatever I want - just not however much I want. Details here.