Is it true: Library of Alexandria Destruction?

There's no solid evidence for it.

The Great Library of Alexandria (Mouseion) was established c. 3rd century BC by Ptolemy I. Multiple destruction narratives compete: (1) Caesar's 48 BC accidental fire during Alexandrian civil war — mentioned by contemporary sources (Caesar himself, Plutarch, Seneca), likely destroyed storehouses of books near the docks but not necessarily the main library. (2) Theophilus of Alexandria's 391 AD destruction of the Serapeum (a daughter library) — well-documented in contemporary Christian sources. (3) Caliph Umar / Amr ibn al-As's 642 AD destruction — first appears in 13th-century Arabic sources (Ibn al-Qifti), generally treated by modern historians as medieval fabrication; no 7th-century source supports it. Most classical historians (Canfora, Bagnall) suggest the Library declined over centuries through multiple partial destructions, neglect, and changing political-cultural conditions — not a single dramatic event.