According to this article: https://news.yahoo.co.jp/expert/articles/8a8ee1190b305bc4a52...

The main issues are thought to be Tampering with airbag timer ignition Falsely recording test results Falsification of test speeds Falsely recording tire pressure Replacing the acceleration data of the upper portion of passenger seat

The article goes into more depth re each item, DeepL is your friend if you don't read Japanese

There’s still very few details on the technicalities of the safety issues, anyone more informed?