What does Strahnbrad Mystery reward?

Strahnbrad Mystery gives Brilliant Cloak outright, 40s.

Where does Strahnbrad Mystery start?

It was picked up in Alterac Mountains.

The quest log lists it at level 36.

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

World of Warcraft: Forever · quest · level 36 · new since Classic Era

A level 36 quest in World of Warcraft: Forever in Alterac Mountains and turned in to Shara Blazen. Recorded by 3 players running the addon.

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

Item	Given	Item level	Vendor sell
Brilliant Cloak	outright	41

What does Strahnbrad Mystery reward?: Strahnbrad Mystery gives Brilliant Cloak outright, 40s.
Where does Strahnbrad Mystery start?: It was picked up in Alterac Mountains.
What level is Strahnbrad Mystery?: The quest log lists it at level 36.
Is Strahnbrad Mystery 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 30 to 40 gold guide.

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