Blocks Broken On Client-side Only? How?

This one question... it's plagued me for years, and i cannot find how you did this?
When you break a tree in Wynncraft, it does not show for others, like, if i break a tree using an axe, the other player will still see the tree and be able to chop the tree down, how does this work?

Please answer my question, this has plagued me for too many years and i finally decided to get up and ask..

 

This video at 9:32 shows the structure blocks used for the trees a bit, no in-depth explaination but it's something to do with structure blocks.

It's important to note that the tree is still there when it is cut, the blocks you don't see anymore still exist. Just try walking into the part where the tree was previously cut. I also don't think it ever "spawns" blocks as you cut the tree (other than at the tutorial for the bridge if that even is in the new tutorial) It might replace some blocks but no new ones are placed. Which means that there's only a visual change.

 

the magic of command blocks

and structure blocks