Regulation (EU) 2024/1328 of 16 May 2024 amended Annex XVII of the European REACH Regulation (EC) No.1907/2006 to introduce new restrictions on D4, D5 and D6.

From this 6 June 2026, D4 (CAS No.556-67-2, EC No.209-136-7, INCI: Cyclotetrasiloxane), D5 (CAS No.541-02-6, EC No.208-764-9, INCI: Cyclopentasiloxane) and D6 (CAS No.540-97-6, EC No.208-762-8, INCI: Cyclohexasiloxane) are prohibited (as substances on their own, as constituents of other substances or in mixtures) in rinse-off cosmetic products at a concentration of 0.1% by weight or higher.
This restriction has already been in force for D4 and D5 since 31 January 2020.
It will apply to leave-on products from 6 June 2027.

Source
• Regulation 2024/1328: new restrictions for D4, D5 and D6, CosmeticOBS, 21 May 2024