Judgment of the General Court (Sixth Chamber, Extended Composition) of 19 November 2025.#Nouryon Functional Chemicals BV and Others v European Chemicals Agency.#REACH – Substance di-tert-butyl 1,1,4,4-tetramethyltetramethylene diperoxide – Compliance check of registrations – Request for additional toxicity studies – Article 41 of Regulation (EC) No 1907/2006 – Manifest error of assessment – Error of fact – Proportionality – Decision of the Board of Appeal of ECHA – Admissibility of the arguments directed against the decision of ECHA.#Case T-1122/23.