I searched for this but could not find it reported. I tried to select iPhone 8 and 8 Plus because it happens on two different phones, and also on iPad Mini and 4th Gen.  Selecting iPhone 8 was not an option on the list.

In my family we call this "Punching Hand Syndrome." When using touch on iOS devices (but NOT when using a Nimbus controller) Steve often get's "stuck" mining.  We might harvest a few carrots, but then we get Punching Hand Syndrome and the next thing you know . . . the dirt is punched out and the wall is broken and unless you're pretty quick to point up into the air, it can cause a lot of damage.

We have found that pausing the game reliably stops an episode of PHS.  

I don't remember exactly when this started, but it started all of a sudden one day and it was a while back, before the Update Aquatic.