It is a bug.
While latest update did tweaked the machines a bit, it mainly touched harvesters:
In this update we’ve also taken our first steps to updating the machine behavior, primarily in combat. Much of this is beneath the surface and won’t be immediately noticeable, but as you go up against the machines more you may notice a few changes to how they approach combat - specifically a new behavior for the Harvester that may surprise you!
Source: https://generationzero.com/en/blog/april-update-patch-notes
And now we know that the new behavior of the harvester is their ability to call in hunter pod airdrops.
Military hunter’s gas mortar and resulting damage from it’s gas got also increased and here i don’t know if it was intentional or part of the bug as well.
However, the pinpoint accuracy of rocket pods on harvs and tanks + their non-stop fire rate, are bugs, since from the launch of GZ, no machine has ever had that kind of god level accuracy and fire rate.
Machine aggro range seems to be bug as well since before, you had some time to evade (proximity arrow turned white if machine was close; turned yellow when machine heard you; and turned red when machine locked on you). But now, there is no gradual warning, instead machine locks on you at the instant you get into it’s hearing range.
If you’re host, then from game settings, turn auto-scaling OFF. This reduces the machine amount down to 1 player game, even when you have 4 players in your game.
And the best pro tip (it’s actually a secret): harvs and tanks have limited weapon range of 200m.
Meaning that if you are more than 200m away from them, they may try to shoot at you but none of their bullets/rockets are spawned, making you completely safe from them. Then it’s just matter of sniping them for afar.
Though, not all machines have their weapon range limited to 200m. Concussion Rifle (military and FNIX hunters) has a range of at least 300m, if not more (haven’t tested the exact range yet).