As reported in other blogs (see for instance here and here), the Trade and Cooperation Agreement that the EU and the UK managed to conclude right before the end of the Brexit transition period does not seem to make any provision for judicial cooperation in civil matters.
On the European side, the Notice to Stakeholders issued by the European Commission in August 2020 already took lack of agreement in this area for granted.
Surprisingly, the press release of the Commission of 24 December 2020, under the heading “A new partnership for our citizens’ security”, states
The Trade and Cooperation Agreement establishes a new framework for law enforcement and judicial cooperation in criminal and civil law matters. (italics added)
And to top it all, have a look a recital 47 of the Recast Service Regulation:
In accordance with Article 3 and Article 4a(1) of Protocol No 21 on the position of the United Kingdom and Ireland in respect of the area of freedom, security and justice, annexed to the Treaty on European Union and to the Treaty on the Functioning of the European Union, the United Kingdom and Ireland have notified their wish to take part in the adoption and application of this Regulation.
Probably just a clerical mistake.
On the UK side, the gov.uk website on Brexit was updated on 31 December 2020 (see here), providing information on the rules applicable to cross border cases in civil and commercial matters involving the courts of England and Wales. Links to all relevant Acts and Regulations are found there, too. For cross-border divorces, nothing has been added to the previous information, which already distinguished between proceedings initiated pre- and post-Brexit. The same applies to maintenance and disputes about parental responsibility.