Since chunk loading based on block updates was completely removed in 1.14, Redstone is no longer deterministic when it comes to chunk borders. This can cause Redstone contraptions to break completely when activated while on a chunk border.

In 1.13, this wasn't a problem at all, as the block updates from the redstone signal simply loaded the other chunks and allowed the contraption to work. In 1.14 however, no such thing happens and only half of the contraption does something, while the other idles. Especially in timing based contraptions, this can have fatal consequences and may break the entire build.

I've attached a world save where this exact phenomenon can be observed. I built a Redstone door on a chunk border and added a lever from two chunks away. If the render distance is set to two chunks, actuating the lever breaks the door so that it needs to be repaired manually.

This does not only happen with ultra short render distances; one can easily imagine a situation where a mob or minecart actuates a contraption which is partially unloaded.

As Redstone has always been deterministic and independent of chunk loading, I hope that this will be fixed as soon as possible.