Yes you can absolutely dye your hair when breastfeeding. There is no evidence that dying hair affects breastfeeding! Only that baby might not like the smell :) this is a myth! https://sg.theasianparent.com/dye-hair-while-breastfeeding/?utm_source=search&utm_medium=app
You may refer to this link https://sg.theasianparent.com/can-a-breast-feeding-mom-dye-or-perm-their-hair Perhaps don't dye so often or better still to avoid.