slacken off vs ease up

slacken off and ease up both are verbs.

Word	Noun	Adjective	Verb	Adverb
slacken off	No	No	Yes	No
ease up	No	No	Yes	No

As verbs, slacken off and ease up are synonyms defined as:

Other synonyms of slacken off include ease off, flag.

slacken off (verb)	ease up (verb)
become less intense	become less intense
	reduce pressure or intensity
	move in order to make room for someone for something