(a) It must be in the approved form, i.e. ‘Allahu Akbar’ without any addition or change and without joining it with other wordings.
(b) It must be in correct Arabic.
(c) It must be said while standing (details will come afterwards).
(d) Body must be in ‘tamaninat’ (not moving, but still).
(e) Muwalaat: The letters and words should be recited one after another without gap.
https://www.al-islam.org/elements-islamic-studies-allamah-saeed-akhtar-rizvi/lesson-32-niyyah-takbir-and-qiyam
My preliminary conclusion is that none of them are fluent speaker of Arabic, and can not even follow a written text. They are just reciting.