The state variables feeOnTransfer is never initialized which leads to a default uint value of 0. When it is used on L126 in the first call to _transfer(), it will lead to a zero fee. feeOnTransfer is updated only in function _checkEmission() whose call happens later on L133, after which it has a value as calculated in that function. This causes only the first transfer to be a zero-fee transfer.
Recommend initializing feeOnTransfer suitably on declaration, in constructor, or init() function.
