@farbenstau Bzzt source cited does not collaborate claim:
https://web.archive.org/web/20230601113438/https://www.eisenbahn-unfalluntersuchung.de/SharedDocs/Downloads/EUB/Zwischenberichte/2022/87_Zwischenbericht_Garmisch-Partenkirchen_-_Farchant.pdf?__blob=publicationFile&v=2 does refer to them having damages not defects. Accodring to local press a previous conductor on the same line the day before reported a visual anomaly. https://www.br.de/nachrichten/bayern/bericht-zugunglueck-burgrain-vorwuerfe-gegen-fahrdienstleiter,TqrW01Y
This kinda all points against a link to Concrete Cancer unless you got newer German primary sources you are likely wrong IMHO.
Also no legal proceedings were started again the company which made the damaged part, this further speaks against
@farbenstau a systematic error (bad chemistry). While there is reporting of special inspection where many of this type were replaced this isn't phrased in a way that suggest a type wide issue. https://www.sueddeutsche.de/bayern/zugunglueck-garmisch-partenkirchen-unfall-fuenf-tote-ermittlungen-bahn-mitarbeiter-1.6244651
Do you have any evidence explicitly linking this to Concrete Cancer?