The Arabic letter Ẓāʾ (ظ) is pronounced differently in Classical and Modern Standard Arabic.
Classical Arabic: It represents a velarized voiced dental fricative, which is phonetically transcribed as [ðˤ].
Modern Standard Arabic: The pronunciation can vary slightly, being either a pharyngealized voiced dental [ðˤ] or alveolar fricative [zˤ] depending on the context and the speaker's dialect.
In many Arabic dialects, Ẓāʾ and Ḍād (ض) have merged, leading to pronunciation differences based on regional variations.
For more detailed information, you can refer to this Wikiwand article.