Why did chinese believe the tang struggled with crop failures and government problems?

During the latter part of the 9th century, the Tang Dynasty was confronting numerous challenges regarding public administration and natural disasters. After a disastrous flood in 858 which caused many casualties and a failed harvest in 873, the Chinese people began to believe that it was a "Mandate of Heaven" that the Tang Dynasty should come to an end.

is this like a kind of true or false question?

here is a link that will you.