I am going to explain by example....
Here is the same phrase in English German and Spanish
The exact same content is considered unique and different if it is in a different language.
Genau derselbe Inhalt gilt als einzigartig und unterschiedlich, wenn er in einer anderen Sprache vorliegt.
El mismo contenido exacto se considera único y diferente si está en un idioma diferente.
Another reason is this .....
What percentage of the world is bilingual 2020?
Monolingual:
A person knowing only one language (40% of world population)
Bilingual:
A person using or able to use two languages especially with equal fluency (43% of world population)
Trilingual:
A person speaking three languages fluently (13% of world population) Never mix languages on a page.
It confuses your visitors, and it confuses Google and other search engines as to whom your target audience is.