Both Uses

discretion
in
The Phantom of the Opera
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He quite failed to see that the indiscretion of his conduct was exceeding all bounds.†
Chpt 2 *

indiscretion = behavior that displays a lack of good judgment

standard prefix: The prefix "in-" in indiscretion means not and reverses the meaning of discretion. This is the same pattern you see in words like invisible, incomplete, and insecure.
The stranger kept up the gesture that recommended discretion and then, at the moment when the astonished viscount was about to ask the reason of his mysterious intervention, bowed and disappeared.†
Chpt 15 *

Definitions:

(1) (discretion as in: It is within her discretion.)
the right to make a decision (and perhaps accompanying good judgment)
(2) (discretion as in: embarrassing lack of discretion)
behavior that does not attract undesired attention or reveal private information
(3) (discretion as in: Parental discretion advised.)
good judgment or good taste
(4) (meaning too rare to warrant focus)