Is it a window frame or the picture frame??
Interesting how in the unrestored image you can see the darker shade on the wall where the cupid image shows through just a bit.
I believe it’s a window. You can see a reflection of the background window in the sill of the restored painting. The second artist also filled in some details above the curtain rod (continued the red curtain).
Your right, you can see the covered image of cupid enough to know something was there. Maybe if the cupid painting were not so large and prominent, it wouldn’t have been covered up.