can someone explain to me this classic weight maintenance bug

[wollet2]

it says in the calculator that i need around 1950 calories / day to maintain my weight, given height, age, excervise etc

but i 100% hit much lower than that daily and i dont lose weight. im +-2kg depending on how much water i drink

so what is happening

 

[wollet2]

fitness is such a scam and broscience jfl

nobody knows shit