How can a hadith containing the phrase "may your mother be bereaved of you" be authentic, and did the Messenger of Allah, peace and blessings be upon him, supplicate against his Companions with this word, which means "may your mother lose you," or does it have another meaning?

The Hadith is authentic, and the phrase "May your mother be bereaved of you" is customary among Arabs and is not intended as an invocation of ill will. The Prophet's ﷺ supplication against believers is a mercy and a virtue for them, as is established in the noble Hadith: "O Allah, I take an oath before You which You will not break: Verily, I am but a human being, so for any believer whom I have hurt, reviled, cursed, or lashed, make it a prayer, a purification, and a means of drawing closer to You."