Server restores blocks by itself

I need to destroy a large part of the world so I decided to use arrays of TNT to do so.
So I place a line of TNT's and detonate them by using redstone on the first TNT.

A line of huge explosion occurs and a massive destruction was achieved as planned, but I noticed the server started restoring the blocks that were damaged by the TNT's one by one gradually.

My server has no Anti-griefing plugins installed. If any it would be HawkEye.

I have not made any changes to the server and I only updated the plugins after 3 months of absence, and I was wondering what would be causing this problem.

Anyone has an idea?

 

Earlier versions of WorldGuard would show destroyed blocks, and they would rebuild like you describe. If your WorldGuard config has 'block-tnt-block-damage: false', then another plugin is intercepting these events.

 

If you have creeperheal you must remove it