My brother, a mexican citizen, will inherit my ira. Is any tax due in mexico?

This tax forum only addresses taxes in the United States.

That said, I would think it likely that the Mexican government WOULD tax the IRA distribution to the heir.

For sure, the U.S. government is going to tax the distribution if the IRA is a traditional IRA, because the custodian will withhold 30% of the distribution before sending it overseas.