The Smoke Surface Emission is the height of the smoke from the mesh surface.
It is measured in Domain Grid Units, and if the grid unit is relatively big
(compared to the mesh), the smoke emission is huge.
To fix that the Surface Emission was decreased from 1.5 to 1.0. As a result
it is possible to emit smaller smokes (width 2, previously 3).
Further decreasing default value of Surface Emission is not recommended,
as in some cases (too small mesh compared to Grid Unit) will result not
emitted smoke.
Fix#132613: Issue with large smoke domain and small emitter
Pull Request: https://projects.blender.org/blender/blender/pulls/138567
6f1e0a8adf