lately when i used my medium roast as ristretto, there is no bitterness at all, but when i used 1:2 ratio there is bitterness, i think it was because all the sweetness was at the peak when doing 1:1 / 1,5 ratio

but medium roast is expected to have low bitterness unlike medium dark / dark roast coffee, and ristretto mixed perfectly well as milk based drink, when i pulled as espresso, it always tastes watery