Pronunciation of certain Arabic letters

منذ ٦ أعوام

 
I found this alphabet on Al Jazeera
https://learning.aljazeera.net/fr/generallanguage/الحروف-والأصوات-العربية-جدول-الحروف
and was surprised by the pronunciation of the following letters
‎  ث / ذ/ظ
They are pronounced practically T / D/ D like in certain dialects
Is this specific to Qatar accent?
How is it in Fus’ha?