5 kg target challange for july ??

Ill try 3-4 kg

first of all. to lose muscle you really have to try hard! a lot of people confuse muscle with intramuscular water (aka my arms are flat compared to offseason so i must be losing muscle).

And 5 kg in a month are not that unusual. especially if you are not in a caloric defficit when you start the challenge so the first 2kg are initial water drop. and you are starting from a higher bodyfat percentage.
And most people who claim 5kg are way too much don't diet properly and don't do enough cardio.