I'm a fellow user, not a tax person. But this is my basic understanding in general of how the foreign income exclusion can affect the tax rate, and does not address your specific figures.
When you have the foreign income exclusion, the excluded amount is applied first to the lower tax bracket rate(s) and thus precludes the lower rate(s) from being used by the taxable income (or part of the lower rates depending on the amount of the exclusion.) So the excluded amount throws aside all or part of the lower bracket(s) first so that the lower rate(s) is/are no longer available to the taxable income. So the remaining (non-excluded) income ends up taxed at a higher bracket rate. Therefore the tax amount is higher than using the IRS Tax Tables alone.
