A breaking change is a change that may require you to make changes to your application in order to avoid disruption to your integration.

7.1.0

Dynamic Localization Removed
AppNotification Removed
TitleBarHelper Removed
ThemeService Some Methods Removed
ListViewExtensions Removed
AssemblyInfoHelper Removed
GetLocalFolderPath renamed to GetAppDataFolderPath
JsonNavigationViewService Methods Modified
NativeMethods class replaced with CsWin32 Library
AssemblyInfoHelper removed and Replaced with ProcessInfoHelper
WindowHelper Methods Modified
ImageIconPath removed and replaced with IconGlyph proeprty in Json File (JsonNavigationViewService)
nucs.JsonSettings dependency removed from Core library

See here for full changes