Haggai says the LORD struck the work of their hands “with blight and mildew and hail” Haggai 2:17. The verse presents these as part of the hardship they experienced.
In Haggai 2:14–17, Yahweh applies a purity lesson to the whole community: they themselves, and therefore everything they do and bring, is treated as unclean. Haggai then urges them to look back over the period before rebuilding resumed, when their expected harvests repeatedly came up short. These verses sit inside Haggai’s fourth dated message (2:10–19). Just before this, Haggai asks the priests two questions about ritual transfer: holiness does not spread easily by contact, but uncleanness does (2:11–13).
Haggai 2:14–17 applies the priestly rulings about impurity (2:11–13) to the whole community. Yahweh declares that “this people” and “this nation” are unclean “before me,” and that this uncleanness reaches what they do and what they bring as offerings (verse 14).
A careful answer keeps the immediate passage, the book's argument, and the whole-Bible storyline together, so the question is answered in context instead of as a detached idea.
Start with Haggai 2:17, then read the surrounding section so the answer stays connected to the passage's flow.
17I struck you with blight, mildew, and hail in all the work of your hands; yet you didn`t turn to me,` says Yahweh.