This should be the issue reported as bug FDO#87532. I cannot confirm that it only applies to the fonts ‘Arial’ and ‘Times New Roman’ for which it is reported there.
As my test is showing the problem will also occur in documents not imported from alien files. ‘Insert’ > ‘Special Character…’ > (some Arabic letters) > change font style to ‘Italic’ will produce it in most cases. Many additional fonts (if not most) are afflicted.
As I don’t know anything about writing in Arabic (except that it is running from right to left … and always ‘Italic’ in a sense) I cannot say if the ‘Italic’ style has any meaning for it and if fonts (which ones?) contain an ‘Italic’ variant or if the ‘Italic’ style should be faked or ignored by the running software …
As the handling of fonts is the same for all of LibreOffice the problem will also show in Writer documents.
My best idea: Negociate with your partners to not use ‘Italic’ in Arabic writing.