What's Under the Black Rectangle?

As the title suggests what’s being covered on Beast, Tiny Torch, Grey Widow, CMags and Classic Storm’s covers?
And while we’re on it can’t something be done about them they look really out of place?

Placed an example below but spoilered it for those who want to go hunting

Probably Barcodes.

50 Years of Captain America

Breasts. Oh wait, that’s reality TV.

Yep, that’s where the barcodes would go on covers of that era (they’re all circa early 90s).

Excuse my ignorance but why do they need to be covered??

There were usually two versions of a cover - one would have a barcode for the places that needed it, the other would have a little Marvel logo or something for the direct market (i.e., comic books stores). The artwork would just leave that blank, to be replaced by whichever was required, hence the black rectangle.

The black rectangle is very welcome compared to whats on Captain Marvel’s cover art. It’s horrendous and embarrassing

You are correct sir!

Like the seamless ad for The Winter Soldier?