It doesn't appear that Antoni Gaudí had anything to do with the etymology of the term "gaudy" as it was in use hundreds of years before he was born.

https://en.wiktionary.org/wiki/gaudy https://www.merriam-webster.com/dictionary/gaudy

I couldn't help looking it up because the idea that a single artist could stand out so much to be singularly associated with that term was tempting. I expect that is why such a false association persists.