The prisoner gets Mining Fatigue 3. This means breaking obsidian takes 25 hours. The prisoner is kicked from the server every ~8.5 hours which disrupts the mining.
Outside defence
There are two floor detectors, one to detect pearl glitching and one to detect using the squilly end exploit. Above the prison there are more tripwires to instantly detect if someone gets on top of the prison. All around the prison are hundreds of armoured piglin bans, and around them are hundreds of thousands of anvils to kill withers.
More Security
The visitor killcheck is a respawn anchor with only one glowstone, making the exit process much easier and the end exploit impossible.
