Is the claim that the Hadith "Tomorrow I shall give the standard to a man..." is unauthentic, on the pretext that it was narrated by Companions who did not attend the Battle of Khaybar, considered a valid doubt?

The prophetic hadith, "Tomorrow, I shall give the banner to a man through whom victory will be granted; he loves Allah and His Messenger, and Allah and His Messenger love him," concerning Ali ibn Abi Talib during the Battle of Khaybar, is an authentic hadith agreed upon, narrated by Al-Bukhari, Muslim, and others from a number of Companions. The narration of hadith by a Companion who did not hear it directly from the Prophet, peace be upon him, but rather from another Companion, is considered authentic and acceptable, and this is called "Mursal Al-Sahabi" (a Companion's mursal narration). Scholars have unanimously agreed on its admissibility as proof. Abu Hurairah, Sa'd ibn Abi Waqqas, and Salamah ibn Al-Akwa' all witnessed the Battle of Khaybar and narrated the hadith, having witnessed some or all of its events, and some of them explicitly stated hearing it from the Prophet, peace be upon him. Many authentic hadiths have been reported regarding the virtues of Ali ibn Abi Talib, which have been compiled by Sunni scholars. It is forbidden to insult the Companions, including Ali ibn Abi Talib, for he is among the foremost early Muslims with whom Allah is pleased. The diligent Muslim must avoid sitting with and listening to those who promote doubts, because hearts are weak and doubts are snatchers.