Votes to close are known to expire, for the reasons explained eg in answers to this question: Why do close votes expire?
Does something like this happen to flags to close cast by users lacking CV privileges?
Side note - related question makes one feel that it's unlikely the case: Don't let flag-to-close flags linger for months in flag purgatory
I ask because per recent changes flags like that are no longer targeted to moderators only, but instead, go to same review queue as votes to close. This makes one wonder if the reasoning for votes expiration can now be applied to flags.