Do Arabs really speak with lengthened sounds?

In Tajweed, especially in this [YouTube Channel](https://www.youtube.com/@Arabic101) , it is emphasized that some sounds should be lengthened up to 4 seconds. I am not a linguist, and I am not a historian. Yet I know many languages in different levels (Persian, English, a little French, Quranic Arabic, Kurdi, Turkish), and in none of them, there is this concept of elongation of sounds. And while I fear Allah and don't want to be a critic, it seems strange to me to think of Arabs contemporary to our Prophet (PBUH) who would speak with sounds that take 4 seconds to pronounce. This makes me suspicious of the Tajweed rules altogether. Can someone please explain where this comes from and how we can trust that it's true?