See blender/blender-assets!15 for the actual asset file change. As part of the brush asset project, various weight paint brushes had their falloff curve changed. This had the unintended effect of changing the behavior of the gradient tool, as it shares the currently active brush's settings. This behavior is unintuitive and not well documented, as an interim fix, the bundled assets were reverted. Pull Request: https://projects.blender.org/blender/blender/pulls/131058