Service performed in Brazil for customer in Spain, paid in US

resident of Brazil and recently did a job for a Spanish customer

As the service is rendered from Brazil, the tax would be accrued in Brazil. Depending on how your contract was structured, there maybe an element of tax in Spain. However that should be the look out of your Spanish Customer and not you.

who paid me in the US.

From a tax point of view, it is generally irrelevant where the payment is made as long as it is convenience; i.e. the payment could also equally have been received in Brazil. Thus there is no tax liability for this in the US.

Note this is different from requirements of operating a Bank Account in US. You may still be liable to questions with respect to your Bank Account in US by US authorities if it is missing adequate documentation. The IRS may treat this as income deemed received in US if there lack of adequate documentation to establish that the income was NON-US