eBay doesn't make spot checks on items sold. If they have issued a safety warning, they will be passing on a recall notice or similar from the manufacturers.
For who's responsible, please see my reply on the same subject on the "Dyson V6 vacuum" question.
Most after-market batteries are from China. On items imported direct from sellers in China CE marks may be faked, or may be a Chinese lookalike CE mark. This is almost identical, only difference being slightly different spacing between the letters. The Chinese disingenuously claim that this mark means "China Export"!