Someone customized the advanced approvals bundle. You're looking for the email template used. It's not referenced in a parameter, a library, any NSTS script, a workflow variable, the Email templates list, or the adv pdf list. The body text is clearly customized to your company but you can't find the source. What are you overlooking?

What an odd way to phrase your question. Did you look at what email template you're using on the relevant Custom Form? E.g. the vendor bill or journal entry form? See what's selected in the "print template" and "email template" fields and that should tell you what template you're using where (there's lots of different things that can affect this, even user preference settings can affect which one gets used in various scenarios).

Turned out all the scripts were disabled and a private saved search with a scheduled email was sending it. Simple, undocumented, functional.

Ha. Glad you found it. It is super annoying how admins can't global search saved searches until they're explicitly added to the audience.

I once again find myself advocating for Salto.. I really must ask for a commission... Once you've got your saved searches being fetched in Salto, if can do a search for

FIELD_EMAIL_SUBJECT = "subject of email"

to find the search that is triggering it. You could even just search for the subject alone, as that would probably also find any workflow, script, etc that had the subject line in-code. You can also more generically search for

FLAG_(TRIGGERED|SCHEDULED)_ALERT = true

(regex search) to find all scheduled/triggered email saved searches.