math Operation +% for price product not correct

[TAIWAR]

VM 2022a

hello
I create product price 100€
Shopper A have for this price 100x1,3=130€
shopper b have for this price 100x1,2=120€
In tax and rules
I selected the modfier price (first line) and math operation +%    valeur = 1,3
but the probleme is that the result is 101,3€ and 101,20€
is a bug or what wrong please ?

[AH]

Value shoud be 30 and 20

NOT 1.3 and 1.2

[TAIWAR]

Thank you very much

[AH]