Mischievous (outsourced?) graphic designer?
Perhaps someone who knows more about typesetting can explain, but it doesn't look like your average computer cockup.
It looks very much like an average cockup - a result of using a simple image editor, I would guess.
The original Trump message image was "wiped" by filling it with black. Odd not to use a new image but I bet it was done to avoid an audit trail to the file as a Trump congratulation message.
However, it looks as if the colours in the fill process weren't adequately defined. The image was not a simple black/white one and looks to have been a jpg, the compression for which adds grey shades to transition areas between black and white.
If you replace the black with a lighter colour, even with a simple bucket fill in Irfanview, the bits of original text show up. If they had used a non-compressed image format, this wouldn't have happened.