-4.2 lbs of muscle but only -3.3% of body fat lost. How accurate is RENPHO?

3rd week on my first cycle of Reta .

Still eating atleast 150 g of protein a day with heavy solid lifting 4-5 a week. I don’t feel or see any noticeable strength loss but losing almost 5 lbs of muscle mass sucks.

How accurate are these digital scales as far as percentages go if you are comparing data with the baseline measurements it read originally?