Is this Gimp 2.10 (or Gimp 2.8)?
I can not reproduce that, please post a full screenshot showing the tool settings, layers, brushes.
Similar to this: https://i.imgur.com/Stgk1LU.jpg
There is a hard edge toggle, check that, maybe the brush dynamics as well. Make sure the Mode is RGB not Indexed.
I can not reproduce that, please post a full screenshot showing the tool settings, layers, brushes.
Similar to this: https://i.imgur.com/Stgk1LU.jpg
There is a hard edge toggle, check that, maybe the brush dynamics as well. Make sure the Mode is RGB not Indexed.