The Spanish government don't want to see the flag of the independence of Catalonia
The Spanish Government announced that Estelada flags will be banned in Copa del Rey final to be on Sunday between Barça and Sevilla.
For now, the club has not expressed their opinion on the prohibition. A few months ago, the club was sanctioned for supporters waving that flag in the Champions League final against Juventus.
To understand the conflict with Estelada flags, you can read this article: "What's the matter with FC Barcelona, UEFA and 'estelada' flags?"