Greek's gift
Greek gift is a popular expression used to represent the receipt of a gift or gift that brings harm to the recipient, contrary to what was expected.
This expression refers to the Trojan Horse, a famous episode described in Homer's Iliad, which narrates the events of the Trojan War.
In the Trojan War, a wooden horse was left at the Trojan walls by the Greeks, supposedly as a gift. The Trojans took the horse inside its walls, believing that the supposed gift was a surrender of the Greeks.
However, inside the horse were several Greek soldiers. During the night and after the Trojans got drunk and most of them were already asleep, the Greeks opened the gates for the entire army to enter and destroy the city completely.
Hence the expression "gift of Greek", something that apparently looks good, but turns out to be a big headache. It represents a benefit that in the end proves to bring only harm or minimal inconvenience.
Source: https://www.dicionariopopular.com/presente-de-grego/