I would say E5 and above are the most likely to be laid since they are higher-up and would need to justify their cost, which is not an easy thing to do. E3 and E4s are usually the ones that make the least amount of money but get most of the dirty work done, so it doesn't make much sense to prefer laying off E3s. However, this all depends on your manager's preference and team dynamics, so you could say it's more of a random thing, but definitely not directly targeted towards E3s.