There are several redstone systems that, when loaded upon opening the world, start to operate differently.
For example: there is a hopper that is clearly blocked by a redstone charge. In front of it, there is a dispenser that, if activated, sends one item to the hopper. This dispenser will only be activated if an observer detects a change. I check my hopper and see that there are no items inside it, but upon  closing and opening the world, in this same example, an item ends up inside the hopper without anything being moved, and one item decreases from inside the dispenser.
In addition to this problem, there are other redstone-related systems that stop working. For example, a tower of dispensers that sends items upwards works initially, but if I close and reopen the world, the tower of dispensers stops working and the items get stuck halfway.