What does Essence of Seeping Slimes reward?

Essence of Seeping Slimes gives a choice of Slime-Resistant Shroud, Reinforced Muck Protectors, 90s.

Where does Essence of Seeping Slimes start?

It was picked up in The Shaper's Terrace.

The quest log lists it at level 60.

Yes. Its quest id is not in Classic Era, so it is part of what Forever adds.

World of Warcraft: Forever · quest · level 60 · new since Classic Era

A level 60 quest in World of Warcraft: Forever in The Shaper's Terrace. Recorded by 1 player running the addon.

Giver shows once a player with the addon opens the quest.

Item	Given	Item level	Vendor sell
Slime-Resistant Shroud	as a choice	62	1g 65s 9c
Reinforced Muck Protectors	as a choice	62	3g 99s 43c

What does Essence of Seeping Slimes reward?: Essence of Seeping Slimes gives a choice of Slime-Resistant Shroud, Reinforced Muck Protectors, 90s.
Where does Essence of Seeping Slimes start?: It was picked up in The Shaper's Terrace.
What level is Essence of Seeping Slimes?: The quest log lists it at level 60.
Is Essence of Seeping Slimes new in WoW Forever?: Yes. Its quest id is not in Classic Era, so it is part of what Forever adds.

What sells at this level, and what to keep from these rewards, is in the level 60 gold guide.

Source: what players running the addon saw in the quest windows; the quest text itself stays in the game. Every quest seen