Sigh...
This is a draft of an interpretative document of regulation EC1107/2006 which is in force since 13 years, hence the working document in the title. This is the law.
https://eur-lex.europa.eu/legal-cont...X%3A32006R1107
Nobody can ask you to show proof of disability when doing every day lives activity in the European Union. Last time I checked the EU value medical privacy quite highly.