[George83728]

The UDHR, Article 15, says that everybody has a right to have nationality and can't arbitrarily be deprived of nationality. The EU is not a nation and nobody has an "EU nationality", so depriving somebody of their EU citizenship doesn't violate Article 15. People in the UK retained their nationalities.

[ta1243]

"German citizen" == "Germany nationality"

"Nigeria citizen" == "Nigerian nationality"

"EU citizen" != "EU nationality"

[George83728]

Sounds like you figured it out. Germany and Nigeria are nations, the EU is not. Appropriately, Germany and Nigeria are represented in the United Nations, while the EU is not.