I literally looked all week for information, I looked on gov.com and it didn't say this. They treated UK citizens as EU citizens until the 31st of December 2020. So I don't know how or when this was published!
Also, with Hungary being a member of the EU, they should have the form in clear English but it is very loosely translated and some questions are in Hungarian. It would be hard for people who don't read Hungarian to understand the questions. It's just in shambles.
My friend didn't slip through, Luton allowed him on. If the government requires this document then why are some airports adhering to it and others not. It's really stupid. It's basically a form of discrimination.