I’m ignorant about this as well, but the site the op links says this:

What is happening? Computers are designed to handle the subset of the Latin script required to manipulate American English first and foremost. Every other writing system is an afterthought, and Arabic is particularly poorly served. Most of the images in this archive are the result of non-Arab graphic designers pasting Arabic text into mainstream graphic design software that cannot handle anything but Latin characters and not checking with a native speaker.

So it sounds like pasting actual Arabic text into a context that does not fully support it might cause this