EU nationals can continue to use ID cards to travel to the UK only until the end of September 2021; except for the holders of pre-settled or settled status, who can continue using it until at least 31 December 2025. See: additional guidance on travel during COVID-19.
From 1 January 2021 tougher border rules will apply to EU nationals, which means that foreign offenders sentenced to more than a year in jail will be banned from entering the UK.