Surprised Raze didn't catch this!
It's normal. It's not a bug. It means you failed to protect Astarte or your party was wiped out. I saw that little joke of Larian's everytime I failed in the final fight. It's a little disturbing when it first appears but it is not a bug. It is definitely part of their design. You can hit F8 and return to your last load.
This is why you must save a lot in that final fight.
