The score is not a bug! it is rather a mistake of term. At the end it should say "Socre" and not "HighScore", because the number corresponds to your last score. If you go to the menu, your real high score is displayed. We have already fixed it for the post jam version :)
311 days ago(+1)
Sadly for me the score in the main menu is also wrong, so i think it still might be a bug