What is the authenticity of the hadith: "That the death of the Messenger of Allah, peace and blessings be upon him, is better for us, and that his deeds are presented to the servants"? And what does it mean if the narration is authentic? And should one who disagrees with your opinion on it be denounced?

This hadith (definition) is weak, according to the preponderant opinion of the scholars, though some have deemed it authentic or good.

Its meaning is that his, peace and blessings be upon him, life was good for the Ummah by protecting them from tribulations, innovations, and disagreements, and his death was good for them through his supplication for his Ummah in the heavens, and by opening the door to ijtihad (definition) (independent reasoning), and by abandoning reliance [on him in person], and by proceeding with caution. Allah Almighty adorned Muhammad, peace and blessings be upon him, with the adornment of mercy, so his life was a mercy and his death was a mercy.