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Unpowered SSD endurance investigation finds severe data loss and performance issues
(www.tomshardware.com)
This is a most excellent place for technology news and articles.
I pulled some data off some old Samsung 1TB SSDs that werent powered for 3-4 years without an issue either. I guess they were SLC based on what others are saying.
I guess it's a your mileage may vary situation depending on the exact drive you purchase and probably other factors too.