Scaling is always local and is affected by the parent/hierarchy scale.
You can easily fix the scale to stay same, taking into account the original scale of the bone node. Here is an older post with a resolution for this issue:
Scaling is always local and is affected by the parent/hierarchy scale.
You can easily fix the scale to stay same, taking into account the original scale of the bone node. Here is an older post with a resolution for this issue: