Rome I continued to apply to the UK during the UK-EU transition period. At the end of the transition period (at 11.00 pm UK time on 31 December 2020):
Rome I stopped applying to the UK on a reciprocal basis, except as provided for in part three of the UK-EU withdrawal agreement in respect of contracts concluded before the end of the transition period.
Rome I was converted into UK law as retained EU law, and was amended by UK legislation.