en_tn/deu/29/18.md

whose heart is turning away today from Yahweh our God

Here "heart" refers to the whole person, and "turning away" means to stop obeying. Alternate translation: "who no longer obeys Yahweh our God" (See: rc://en/ta/man/jit/figs-synecdoche)

any root that produces poison fruit and wormwood

Moses speaks of someone who secretly worships another God as if he were a root, and the evil deeds he does to serve that god, and which he encourages others to do, as a bitter plant that poisons people. Alternate translation: "any person who worships idols and causes others to disobey Yahweh" (See: rc://en/ta/man/jit/figs-metaphor)