How is “be downhill” used?

In Gifted (2017), one line is: “It went downhill from there.”

Which movie is “be downhill” from?

The clip at the top of this page is from Gifted (2017).

Idiom

to be easy compared to what came before

Heard in 21 movies

1
be (all) downhill
to be easy compared to what came before
It's all downhill from here. We'll soon be finished.
2
be (all) downhill
to become worse or less successful
It's been all downhill for his career since then, with four defeats in five games.

Definitions from the Oxford Advanced Learner's Dictionary, 9th edition

It went downhill from there.

Said in 7 films · #1