In the Vertex Weights panel of the 3D Viewport sidebar, allow for
normalization of vertex groups when any number of vertex groups are
locked.
As with other normalization operators that handle locked vertex groups,
locked weights are summed, and whatever space is left between that sum
and 1.0 is used to normalize the unlocked weights.
Pull Request: https://projects.blender.org/blender/blender/pulls/134535