Vampire Players: What is happening....

My Vampire Sim was sleeping in her coffin when this appeared above it:
https://www.dropbox.com/s/1zkpoieyqqz5onl/02-25-22_12-01-31%C2%A0PM.png?raw=1
What is this and why is it happening? I have never seen this before and very curious as to what it is.
Thanks in advance for any answers.