These Regulations are made in exercise of the powers conferred by section 8(1) of the European Union (Withdrawal) Act 2018 (c. 16) in order to address failures of retained EU law to operate effectively and other deficiencies (in particular under sections 8(2)(a), 8(2)(b), 8(2)(g) and 8(3)(a)) arising from the withdrawal of the UK from the European Union.
Link: The Customs (Revocation of Retained Direct EU Legislation, etc.) (EU Exit) Regulations 2019
Source: Legislation .gov.uk