That is patently false. In the last election https://en.wikipedia.org/wiki/2021_Catalan_regional_election , Ciutadans got just 5.6% of the vote, and, quoting Wikipedia,

> Pro-independence parties gained a majority of the votes for the first time in an election and increased their parliamentary majority

You might be thinking about the 2017 election, but even then, the fact that Ciutadans had the most votes had to do with the pro-independence parties being split.