The Brexit transition period ended at 11:00 pm on 31 December 2020 and at the end of this transition period, the European Union (Withdrawal) Act 2018 converted existing EU legislation which had direct effect in the UK into UK law and preserved existing UK laws which implemented EU obligations. This has made changes to the prospectus rules, the listing regime, the market abuse regime, the Disclosure Guidance and Transparency Rules and the AIM Rules.
Read a summary of what has changed and what stays the same here.