Eso tiene solución. En Amazon venden un set de pesas para calibración. Siempre lleven 250 gramos con ustedes y pídanle a la cajera que les pese los 250 gramos para ver si la balanza no está alterada:
https://www.amazon.com/Calibration-Weights-Digital-Balance-Jewelry/dp/B08SQ2WTNY
200ml of water should weight 200 grams. If you can accurately measure volume then you can use it to calibrate your scale.
If you are not comfortable doing that then buy this from Amazon
https://www.amazon.com/Calibration-Weights-Digital-Balance-Jewelry/dp/B08SQ2WTNY/
I got Calibration weights aswell.
It's a great scale.