From the Bluelight weblink describing the issue, the products seem to be marketed for customers in the USA and not the UK.
Why should we be worried about 4-CA?
4-CA is a highly neurotoxic substance that destroys serotonergic receptors. For many years, 4-CA has been used in biological research for this reason.
Please do not consume any of these products containing this substance. I urge anyone who is in possession of one of these products to discard or destroy the product through the proper methods.