It’s debatable how “British” those world cuisines are, though. Tikka Masala at least is a dish that was adapted from Indian cuisine, not just copied/imported, and I’d assume that most white Brits don’t make vietnamese or ethiopian food themselves. If Brits ate spiced dishes all the time but each and every one of those dishes was made by restaurants run by people with immigration histories, while all the homemade food that white Brits cook is bland, OP’s meme would still be true, but it’s demonstrably not - even traditional British cuisine contains lots of spices.
It’s debatable how “British” those world cuisines are, though. Tikka Masala at least is a dish that was adapted from Indian cuisine, not just copied/imported, and I’d assume that most white Brits don’t make vietnamese or ethiopian food themselves. If Brits ate spiced dishes all the time but each and every one of those dishes was made by restaurants run by people with immigration histories, while all the homemade food that white Brits cook is bland, OP’s meme would still be true, but it’s demonstrably not - even traditional British cuisine contains lots of spices.