The tips panel extension point has been refactored to be safer and easier to use. See the "Add Tip to Tips Panel" extension point for more details on how to define a tip in 15.1+. Note that any custom tip you may have will continue to work as is, but we encourage you to move the tip definitions from the UIXP parameter to the UIXP content as the old way is now deprecated and will be removed one day (and it's also safer to use the new way).