Ran into this for the first time earlier today. Seems the ppl can capture a city and have this instead of resources available ? there was a couple of cities in the same city with this same 'Cannot Be Plundered' attribute and as wondering how they got this ? how long does it last ? how can i get this ? etc etc as it seems a little overpowered capturing cities and having a free bubble without timer etc ? Is this some sort of glitch ?

yeah I would like to know this too.

It is not a bug, it is the protection that is auto activated when a castle is plundered too much. It is in last patch notes. But I am yet to find how many time it lasts too.

You can still crush them and evict them from the city. You just won't get resources.

Oh yes we did just that, Its concerning that a war game needs so much protection , as that same action would have cost the use of a bubble now they get to abuse this new system for free with total immunity to plunder...

My alt seems to stay that way for a long time. Maybe that buff stays until I can plunder for that account.

Useless bubble is useless, they just dont want us to get resource in game. In my server even a level 27 dude has that protection (highest level is 30 so he is not that low level)

Atleast we dont have to waste the energy only to find out they have a loot bubble so i guess its working as intended? So once activated they have total immunity to plunder and no timer etc either ?
So we got cheap warehouses that protect all the daily income of players, with bubbles they can activate and then total immunity ontop these other protections if they actually lose some resource to an attack ? This is completely absurd. So this is now a war game simulator with no fighting or raiding because the resources are all protected and then even if u find some1 with resources and get to plunder they then get total immunity for the following days/weeks.. capture cities etc .. stil got the immunity, complete protection.
So once again to abuse this just dont upgrade ur walls or garrison and then u get rewarded with total immunity to plunder , with low enough walls the initial attack will provide more protection than u could ever imagine. Struggling to find any reason for this extra layer of protection ontop of the systems already in place(capital , bubble etc) apart from denying plunder on a server wide scale so we have to buy the resources ?
Daily Quest Simulator ? Art of Credit Card purchases ? Can we just get the game from few months ago bak and balanced like the community is asking for instead these poorly planned , poorly implemented updates that nobody wants or needs ? PvP should be the major focus of a game like this , not layers of protection for ppl that just want PvE content...

No offence but I would rather defend the city I live in than worry about my plunder. resources are in how many bases across the map and in pve thats so easy to do.

Just another ridiculously stupid feature that's making everyone want to quit.