What does Thunderbrew reward?

No reward has been recorded for Thunderbrew yet.

Where does Thunderbrew start?

Grimbooze Thunderbrew in Westfall offers it.

Its level has not been recorded yet; it shows once a player accepts it with the addon running.

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

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

A quest in World of Warcraft: Forever, offered by Grimbooze Thunderbrew in Westfall. Recorded by 3 players running the addon.

Level, pay and objectives show once a player with the addon accepts the quest.

No reward item has been recorded for this quest. The offer window fills this in when a player with the addon opens it.

What does Thunderbrew reward?: No reward has been recorded for Thunderbrew yet.
Where does Thunderbrew start?: Grimbooze Thunderbrew in Westfall offers it.
What level is Thunderbrew?: Its level has not been recorded yet; it shows once a player accepts it with the addon running.
Is Thunderbrew new in WoW Forever?: Yes. Its quest id is not in Classic Era, so it is part of what Forever adds.

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