I had a new experience tonight on Pearl. I was given the AntiCheat "hacking is not permitted" warning. This was while using a diamond shovel (no efficiency) underwater on dirt and sand while wearing depth strider II boots and a helmet with respiration III/aqua affinity I. Was it the depth strider/aqua affinity combo that triggered this? Seems a bit sensitive...
I decided to move on to working on my auto-farm instead, but the "action will be taken" was quite ominous, and want to be sure I don't really trip it later!

 

Don't worry This too has happenned to me before; i was helping my friend clear his shop (he was re-making it) and i was breaking all of the glass for him. I get the 'hacking is not permitted' warning and that was the end of it.
Also, i was once 'ender-pearling' around the spawn buildings and i again received the warning that hacking is not permitted.
Long story short, don't worry!

 

I got the "hacking is not permitted" warning like 13 times, with a jump boost potion in effect, a haste beacon in effect, and a speed 2 potion in effect.

 

I realized I should have made my signature say "Caught Tater-Handed"