[2022] Zombie climbs the fence in 2 blocks

Sure, if they can get animations to look good doing it. The 'spider' zombies used to climb, but they looked ridiculous doing it. Now they jump instead. I would suggest that, rather than a random chance, a certain kind of zombie be a good climber, so that you can identify and target those zombies if your base isn't designed well to handle them.

Then we can do the same for digging: give that ability to one type of zombie which may or may not be present in a horde.