External render engines, like Cycles, do not use the paint BVH for
rendering. As part of the stroke update process, normal caches are
tagged as dirty. These normals need to be recalculated to be valid on
the next stroke step.
This commit is a mitigation for the reported issue, but does not
fully fix the underlying issue that causes the cycles data to
be in this state.
Pull Request: https://projects.blender.org/blender/blender/pulls/140503
954dbedc57