This is not a UK thing. I have never seen somali girls with ajanabi wallahi and I am well connected with the somali community and the salafi community aswell.
These ajanabis on twitter probably saw the amount of somali women bashing posts on twitter and forums and thought it's fun to bash somali women if their own men are doing exactly the same thing.
But let's be honest, the bashing (in particular in front of Ajanabi on social media platforms) is 95% coming from misguided girls.