Method to hide default separator lines in a SwiftUI's List. You need to call it in the cell (as a modifier), not the list.

noSeparatorLinesInList.swift

// Call this in the cell, for example CellView().noSeparators()
extension View {
  @ViewBuilder public func noSeparators(
    edgeInsets: EdgeInsets = EdgeInsets(top: 0, leading: 0, bottom: 0, trailing: 0),
    color: Color
  ) -> some View {
        self
        .padding(edgeInsets)
        .frame(
          minWidth: 0, 
          maxWidth: .infinity,
          minHeight: 44,
          alignment: .leading
        )
        .listRowInsets(EdgeInsets())
        .background(color)
    }
}