The "Data Processing Addendum" is a legal document that's meant to ensure a legal basis to get GDPR-covered data out of the EU (in my opinion it's a load of bullshit because it's fundamentally incompatible with the Patriot Act, but that's off-topic and beside the point, as far as you or me are concerned it's lawyer-approved). It's a common document that's meant to replace the Privacy Shield (that has been ruled not GDPR compliant a while ago).

The Data Processing Addendum isn't a loophole to collect data that they don't have a legal basis to collect.