How much protein do I need per day to lose fat without losing muscle?

The baseline recommendation of 0.8 grams per kilogram is set to prevent deficiency, not to preserve muscle while losing weight. In a deficit the body is looking for amino acids, and if intake is low it takes them from muscle.

The evidence across resistance-training studies converges on roughly 1.6 grams per kilogram as the point where additional protein stops adding much. Higher intakes are not harmful in healthy kidneys, but they stop paying.

Calculating from current weight overshoots considerably at higher body weights, because fat mass does not need feeding. Goal body weight, or lean mass if you have a body composition measure, gives a more sensible target.

Distribution matters. Twenty-five to forty grams at each of three or four meals stimulates muscle protein synthesis repeatedly across the day; the same total eaten mostly at dinner does not. For most people the gap is at breakfast.

A 75kg goal weight means about 120 grams a day. That is roughly a palm-sized portion of meat, fish or poultry at each main meal, plus eggs, dairy, legumes or a protein shake to close the gap.

Track it for two weeks, once. Almost everyone discovers they were eating considerably less than they assumed, and almost nobody needs to keep tracking after that.