"I blame Brexit for all this mess" Feel free to blame whom you like. In this case you would be wrong. A potted history courtesy of Wiki. below:
"The political movement began in 1922 when Francesc Macià founded Estat Català (Catalan State). In 1931, Estat Català and other parties formed Esquerra Republicana de Catalunya (Republican Left of Catalonia; ERC), which won a dramatic victory in the municipal elections of that year. Macià proclaimed a Catalan Republic, but after negotiations with the leaders of the new Spanish Republic, he instead accepted autonomy within the Spanish state. In the Spanish Civil War, General Francisco Franco abolished Catalan autonomy in 1938. Following Franco's death in 1975, Catalan political parties concentrated on autonomy rather than independence.The modern independence movement began when the 2006 Statute of Autonomy, which had been agreed with the Spanish government and passed by a referendum in Catalonia, was challenged in the Spanish High Court of Justice, which ruled that some of the articles were unconstitutional, or were to be interpreted restrictively. Popular protest against the decision quickly turned into demands for independence.