Or most of the major fraud happened outside of Germany [1] and like most ponzis/frauds they can seem entirely legitimate on the surface until all the tail ends start becoming shorter and there's no Peters left to pay Paul.

Plus they seemed to have had a legitimate primary business, more than enough to cover their pump & dumping in foreign countries without strong rule of law.

There are always limitations on how much regulators and law enforcement can do and it always seems obvious in retrospect. There's always more that could have been done.

[1] the prior accusations by FT in 2019 mentioned it was their foreign subsidiaries inflating sales figures and recently the money got 'lost' hit a dead end in Asia. Companies often get plenty of time to pay back debts and billion dollar companies are given the benefit of the doubt they can pay it back...