Um… Sources? First time I hear of them digging tunnels.
But even if they did dig tunnels for non-military purposes in the 2000s, they have good intelligence of it being used as a military storehouse (even if you don’t believe their intelligence, which is regarded as one of the best in the world by several nations worldwide, you can hear the same from 7/10 terrorists’ testimonies in captivity). And it’s proven that Hamas’ strategy is digging tunnels for themselves, as in 2014 they used those tunnels in fighting the IDF and for invading bordering villages.