This is one of the Chinese reports on the issue: https://m.thepaper.cn/newsDetail_forward_31048287
Excerpt from the report above (translated using Google):
> The Paper learned from an insider that Anker Innovations' battery cell supplier is already a leading battery cell supplier in the industry, and did not inform customers after it changed materials. In addition to Anker Innovations, the supplier also cooperates with leading power bank brands, so the impact is huge. Although Anker Innovations did not name the supplier, an insider pointed out that the supplier was Amprius.
UPDATE:
There's an exclusive interview by 36kr with one of Anker's VPs: