Spain could have eight teams playing European competitions next season. It will happen if Villarreal wins the final of the Europa League against United (they would play the Champions League) and does not qualify in the League in the positions that give the right to play in continental competitions.
Under normal conditions, LaLiga has seven European places corresponding to its UEFA coefficient. The first four would play the Champions League, the fifth classified and the champion of the Copa del Rey (or the sixth if the winner is already in Europe) would access the Europa League and the sixth (or seventh) would go to the Conference League, the newly created European competition that will be released next year.
If Villarreal wins the Europa League and does not qualify for European positions, next season there will be 5 Spaniards in the Champions League, 2 in the Europa League and 1 in the Conference League.
If Villarreal win the Europa League and also qualify for European positions, Spain would lose one of the Europa League seats and would have 5 Champions, 1 Europa League and 1 Conference seats.
If Villarreal wins the Europa League and also ends up in the Conference League place, Spain would lose that place in the Conference and would have 5 in the Champions League and 2 in the Europa League.
The distribution of European places also varied with the victory of Barcelona in the Cup final, since the champion is already classified for European competitions, the sixth classified passes to the Europa League and the seventh would play the Conference League.
It could have been the case that Spain had up to 9 teams playing in Europe next season. For this, in addition to the case of Villarreal, Real Madrid should have the Champions League and not to get into place in Europeans in the League, both requirements being already impossible this season.