Bi-annual means twice per year! The correct term is biennial which means taking place every other year.
Licenses and certificates didn't instantly come to an end at midnight on the 31st December 2020; They are allowed to naturally expire which is why some EASA certificates will expire on the 31st December 2022. Remember, only those EU examiners who registered and undertook the UK CAA online course
before 1st January 2021 is valid to undertake UK examinations and update certificates of experience.
Many UK schools retained EASA validity and will therefore have EASA examiners on board.