How can a Muslim maintain his reverence in prayer when he sees worshipers not aligning their shoulders, not filling gaps, praying with their arms at their sides, and not coinciding with the Imam but rather following him, especially if they are older and do not accept advice?

What has become widespread from violating the Sunnah (definition) necessitates that those who are aware of it strive in calling to Allah, advising Muslims, and teaching them the Sunnah. A Muslim must strive to advise the one who violates the Sunnah with a good and gentle approach, seeking help from Allah. If they do not respond, their actions will not harm him, and he should turn to his prayer, reflecting on its invocations and contemplating the greatness of his Lord.