Hi!
There are basically two ways this could happen: either some machine had
its clock incorrectly set to 2025 instead of 2005, and was subsequently
corrected, or there's a horrible mysterious bug that corrupts one
particular digit of the timestamp sometimes.
On fr.wikipedia, at the same time the 2025 bug happened, all blocked users
with an expire time not indefinite were unblocked. I don't know if any
blocked user with an expire time after 2025 would not have been unblocked
as there were none.
JYP