Aloha, on 29 May 2018 - 08:53 PM, said:
The padlock is for the nodes I haven't unlocked yet. Not for the ones that do not apply to my current loadout.
Red padlock for an entire tree, but all nodes have yellow ones unless you buy it first. But there is no indication which ones within a valid tree do not apply to your loadout. Fortunately, it's not many or of too great of an importance.