It’s complicated than that. Valencian is at best a dialect of Catalan, the differences are not significant enough to considere them two separate languages.
The rejection of considering Valencian as Catalan has some links to Blaverism https://en.wikipedia.org/wiki/Blaverism a “weird” Spanish nationalist movement from Valencia with marked Anti-Catalan character.
Oficial languages in Spain are Basque, Catalan, Galician and Spanish (obviously). They survive others such as Aragonese, Bable or Extremeñu. Plus the Spanish dialects such as the Southern ones.
The rejection of considering Valencian as Catalan has some links to Blaverism https://en.wikipedia.org/wiki/Blaverism a “weird” Spanish nationalist movement from Valencia with marked Anti-Catalan character.
Oficial languages in Spain are Basque, Catalan, Galician and Spanish (obviously). They survive others such as Aragonese, Bable or Extremeñu. Plus the Spanish dialects such as the Southern ones.