Is it necessary to raise one's voice when pronouncing the letter "dhāl" (ذ) in prayer to distinguish it from "thāʾ" (ث), and is the prayer valid if the "dhāl" (ذ) sounds like "thāʾ" (ث) in pronunciation?

The letters Thaa (ث) and Dhaal (ذ) share the same point of articulation (makhraj) and agree in all characteristics (sifat) except for jah’r (audibility/vocalisation). Dhaal is majhoorah (vocalized/audible), while Thaa is mahmoosah (whispered/voiceless). Jah’r relates to the breath, not the sound. Therefore, whoever pronounces Dhaal like Thaa in Surat Al-Fatihah, their prayer is invalid if they are able to learn. They must also make up the prayers they neglected by not learning. One should be cautious of falling into waswasah (obsessive doubt) regarding the points of articulation of letters.