let's start by saying that pvp-locking was the biggest problem with the game for a couple years (2016-2018) and made the game nearly unplayable
preventing lockdown was a hard nut to crack and took several iterations
in the first iteration of the patch it was introduced that if you attack somebody 15+ levels higher, you get those extra 30 seconds delay
but that did not fix the problem completely because people found smart ways around it that made things even worse
the final patch that seems to have solved the issue for most intents and purposes - was never spelled out in detail so that it is hard to figure out exactly when the extra 30 seconds happen and also hard to find a way around it
i believe that there are two extra precautions: if you are attacked then you get preferential right to attack back for 30 seconds, and in addition your right to continue attacking is discarded seemingly randomly
this random (or seemingly random) feature is what prevents a reliable lockdown strategy from being designed and solves most problems with lockdown pvping
the extra 30 seconds one gets here and there is a small price to pay for solving a huge problem, imho