The locusts in Joel came in waves — the palmerworm, the locust, the cankerworm, the caterpiller — and between them they left nothing. It is a picture of loss that is total and slow, the kind where each stage takes what the last one missed. And the promise God makes is not that the locusts were exaggerated or that the damage was less than it looked. It is I will restore to you the years that the locust hath eaten.
Years. Not the crop, not the field — the time. That is the loss most people carry and least expect to see addressed. The years given to an addiction, an illness, a bad marriage, a season of running from God. The crop can be replanted; the years feel unrecoverable.
Notice too the line just before: my great army which I sent among you. God does not distance himself from what happened. There is no attempt to file the ruin under someone else's account. And the restoration comes with a purpose attached — ye shall know that I am in the midst of Israel.
Restoration in Scripture rarely means the old life handed back unchanged. It means something is given that makes the ruined years no longer the last word about you. The people are told they shall eat in plenty, and be satisfied, and my people shall never be ashamed.