As Sefer Vayikra comes to an end, we would expect some kind of summary or last message of the book of Kedusha (holiness), the book of the Korbanot (sacrifices).

Parshat Bechukotai actually start that way, with the תוכחה, warning Am Yisrael of the consequences of not following the Mitzvot.

However, that's not how the Sefer ends.

For some reason, the Torah adds in one more chapter about the Mitzvah of Erchin ערכין and Tmura תמורה. Seemingly, a very technical chapter about how to evaluate things that are donated.

Why does this mitzvah suddenly show up here??

Why end Sefer Vayikra that way??