When using a keyboard with Spanish/Mexico layout and English layout setting, the § key is position in the place where the ` should be (left side of the 1 key).

This tells you how to fix that:

https://ppolyzos.com/2020/10/09/swap-places-between-tilde-and-section-sign-§-key-in-your-macbook-keyboard/

Archive link in case it goes away:
https://archive.is/kjLoU