Link: Instance Streaming | Documentation - Roblox Creator Hub
The provided code uses the ( . ) operator and passes a CFrame to RequestStreamAroundAsync(). I ran some quick tests in studio and discovered the following:
Player.RequestStreamAroundAsync(CFrame) – Infinite Yield, ( . ) operator, CFrame passed
Player.RequestStreamAroundAsync(Vector3) – Infinite Yield, ( . ) operator, Vector3 passed
Player:RequestStreamAroundAsync(CFrame) – Infinite Yield, ( : ) operator, CFrame passed
Player:RequestStreamAroundAsync(Vector3) – Works, ( : ) operator, Vector3 passed
The example should be updated to reflect the correct syntax. Furthermore, the example should be added to the RequestStreamAroundAsync page itself for convenience.
cc: @Rototally