Is it permissible to ask someone praying in front of me, who is reciting the Quran and dhikr aloud, to lower his voice, due to my inability to concentrate in prayer, and what is the ruling on refusal?

If you are not busy, it is better for you to listen to the recitation of the Holy Quran, because Allah Almighty says: "And when the Quran is recited, then listen to it and pay attention that you may receive mercy." However, if you are busy with an act of worship, you may request that the volume be lowered, according to the hadith: "Indeed, each of you is supplicating his Lord, so let none of you disturb another, nor raise his voice above another in recitation." If he insists on reciting loudly in an annoying manner, there is no sin upon him. However, reciting quietly is better for someone who has a person next to him who is bothered by loud recitation, out of consideration for the common good.