It's a type of phishing, known as spear phishing, where a specific individual or organisation is targeted with a highly customised scam.

Emailing financial departments with fake invoices is a common type of spear phishing scam.

https://en.wikipedia.org/wiki/Phishing#Spear_phishing

Phish Different. - Steve Jobs, 1997

the netsec/infosec industry term now is "whaling" or "spearphishing" where a specifically crafted fake email from a vendor to a payor is send to redirect the wire transfer to a another account, typically an ACH money mule or ignorant/clueles patsy that then forwards the bulk of the funds onwards to a location where it cannot be retrieved.