I postulate that people posting comments in arabic languages on international news sites are by a large majority people who live in the respective countries outside of immigrants that still feel more connected to their country of origin than to the countries they are currently in, comparable to the fact that people posting in german are with a 95%+ probability coming from the DACH area or are immigrants into other countries.
No dogwhistle here. Specific languages point to specific geographic areas where these languages are prominently spoken, and if you are using german on the comment section of the bbc, people will rightly assume that you come from the DACH area.