When you are applying a discount, the base amount is the one tax included which is wrong as we'll apply the tax of the discount product on it. So we are basing the discount computation on the total without taxes and then apply the tax configured on the product. It doesn't work with multiple taxes, but will be handled in future developement in odoo. closes odoo/odoo#36798 Signed-off-by: pimodoo <pimodoo@users.noreply.github.com>