no, it should still have kept the data somewhere else on your computer so even if the game is uninstalled you'll be able to see the extra ending if you cleared syrup!
the way it works (as far as i understand) is that you have a copy of the save data in the game folder (that goes away if you uninstall the game/delete that folder) and another copy in your program files somewhere with all the other renpy games you've played, if that makes sense. so uninstalling only gets rid of one copy of the save data.