I created a Redstone device similar to the one shown in this Youtube tutorial ( https://www.youtube.com/watch?v=24-jNCwNQKk ) prior to the 1.13 update. I'd used it plenty of times before the update and encountered no issues with it functioning aside from me having to fix it a couple of times. What normally happens is that the pistons push the grass blocks back and forth while a dispenser fires bone meal onto it from below, constantly planting more as the shifting of the grass blocks destroys them. My device follows the design pretty well, though I had to mess with some Redstone repeater timings to get it to work, so they might be different than the one built in the video.)  

Once the update happened, me and a few pals played on my Realm together. I clicked the lever to start up my flower farm, and the pistons on one side fired before it froze. I tried to turn the device off, but the lever did not respond. Shortly after, me and all of my friends were disconnected from the Realm (no crash report as far as I remember). Upon coming back into the realm, the latest world backup was loaded (losing only about 10-15 minutes of game progress, thanks to an automatic world backup happening every 30 minutes. )

As everyone had been having some lag, I assumed it was a combination of things causing problems, and went to try the farm again about 10 minutes later (as the lag issues had seemed to cleared up by then.) Again, the flower farm caused everyone to be disconnected. I then destroyed it because I didn't want it to (I assume) crash the Realm a third time.