slack off

[Williambywof]

become less in amount or intensity

[Marquetta]

Slack off means reducing effort and exertion, or becoming less diligent or less efficient in performing tasks or responsibilities. It often refers to procrastination or negligence at work, studies, or other activities that require consistent effort.

[AliceAstes]

The order to ease away the rope or tackle by which anything is held fast; as, Slack up the hawser.