el yeísmo - pronouncing the Spanish ll and the y in the same way, so that, for example, haya and halla sound the sameSpanish example: El fenómeno del yeísmo fue llevado a Hispanoamérica en la época de los descubrimientos.
English example: The phenomenon of yeísmo was taken to Latin America during the Age of Discovery.
Source: el yeísmo - pronouncing the Spanish ll and the y in the same way, so that, for example, haya and halla sound the same (https://www.123teachme.com/spanish_feeds/word_of_the_day/2020/11/26)