Hello Erick
hope that help you , I have check and try to change the colors and the image used in feedback widget and it’s work fine using these class name in my sass file
.sprintrFeedback__sidebar__header{}
.sprintrFeedback__sidebar{}
.sprintrFeedback__sidebar button{}
FYI my current version is 9.12.1 maybe that different from your version.
hope I really understand you and hope I helped you