Reject unique backgrounds marked: SIMILAR IMAGE HAS ALREADY BEEN SENT

I don’t understand anything. I create new backgrounds that are unique. And all of them are simply rejected, while absolutely everything, in whole pack, indiscriminately. But at the same time, they are all unique, there is not a single repetition or copy in them.
It's some kind of mistake? This is strange, and began to happen recently, before, only similar ones were really rejected.
And they even reject vector backgrounds marked: "A SIMILAR VECTOR IMAGE HAS ALREADY BEEN SENT". But this cannot be, these are generally my first three vector backgrounds! And none of them is accepted under the pretext that there have already been similar ones! This is simply impossible!