Searched through codebase for usages of the sidebar-filled icon and found one instance in the SwipeableMessage component.
Swapped out the SWMansionIcon component for the CommIcon component.
NOTE: Going to create individual diffs for all usages of each icon for CommIcons to make the before/after clear. There are only 6 custom CommIcons so this shouldn't produce too much spam.
On the other hand going to do all of the SWMansion icons together in one go.