en_tn_lite_do_not_use/lev/13/55.md

after the item where there was leprosy was washed

This can be translated in active form. Alternate translation: "after they washed the item where there was leprosy" (See: rc://en/ta/man/jit/figs-activepassive)

leprosy

Here this probably refers to mildew. See how you translated this word in Leviticus 13:47.

it is unclean

Something that God has declared to be unfit for people to touch is spoken of as if it were physically unclean. (See: rc://en/ta/man/jit/figs-metaphor)

You must burn the item

Here "you" does not refer to the priest specifically. It just means someone must burn the object.