The way you check EU job applicants has changed. With everyone focussing on the pandemic, many employers seem to have forgotten about that little thing called BREXIT!
From 1st July 2021, you should have implemented new checks to ensure you do not fall foul of the civil penalties for illegal working. The Home office have published an employer partner pack to assist you, however, it can be a bit complicated to follow. https://www.gov.uk/government/publications/uk-points-based-immigration-system-employer-information/the-uks-points-based-immigration-system-an-introduction-for-employers
Make a start by creating a process to check all new employees, this will be in the form of a checklist. You need to know what documents you need and whether they are from list A or list B, this makes a difference to know if they are entitled to live and work in the UK permanently or whether it is a temporary right to work.
As of 1st July 2021, you can no longer accept an EU citizen’s passport or ID card alone as evidence of their right to work. You could also elect to use the Home office right to work checking service but please keep records of the responses. If you use this method, you will require certain information including date of birth and a share code.