Why US Navy is Retiring a 6-Year Old Ship?

On March 31, 2021, US Navy will retire 4 littoral combat ships. Why is that?

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REFERENCES:
https://www.maritime-executive.com/article/freedom-class-littoral-combat-ships-may-have-serious-gearbox-defect

https://www.thedrive.com/the-war-zone/34558/navy-will-mothball-its-first-four-littoral-combat-ships-in-nine-months-if-congress-lets-it

https://en.wikipedia.org/wiki/Independence-class_littoral_combat_ship#cite_note-104

https://www.defensenews.com/naval/2020/07/01/the-us-navys-first-4-littoral-combat-ships-are-out-of-the-fleet-in-9-months/

https://www.public.navy.mil/bupers-npc/reference/messages/Documents/NAVADMINS/NAV2020/NAV20187.txt

Видео Why US Navy is Retiring a 6-Year Old Ship? канала Not What You Think