Charles Ellicott Commentary Deuteronomy 28:33

"The fruit of thy ground, and all thy labors, shall a nation which thou knowest not eat up; and thou shalt be only oppressed and crushed alway;" — Deuteronomy 28:33 (ASV)

A nation which you do not know. —Compare Jeremiah 5:15-17, “A nation whose language you do not know ... shall eat up your harvest and your bread” etc.