This little booger
https://horseeden.com/horse.php?id=28719751
Was supposed to be a Warmblood. I'm very careful when capturing horses to prevent errors such as using the wrong pass, wrong breed ect.

I intended to capture a patterned silver black Warmblood mare from the beach. I used a Silver Black capture pass. I checked all my boxes before clicking on the capture button. But this is not a Warmblood. This is a Knabstrupper. I did not want, nor did I input any kind of data to capture a Knabstrupper.

You likely accidentally selected the wrong capture pass. If you use an appy pass on WB they become KNN, since WB can't be appy.

That's not possible since I don't own any Appaloosa passes. My passes before this capture were Silver Black, Pearl, and Non-Roan.

This is not a bug. There is still a small chance to capture a wild KNN when you are capturing WBs.

In the beginnings this was the only chance to capture KNNs at all - as you were not able to use KNN capture passes or capture KNN directly.