I appreciate the link to differences in differences, I didn't know what to call this method.

The OP's point could still be valid: it’s still possible that macro factors like inflation, interest rates, or tariffs land harder on the exact group they label ‘AI-exposed.’ That makes the attribution messy.

Those fixed effects are estimated separately for each age group, controlling for that.

pg. 19, "We run this regression separately for each age group."