https://arxiv.org/pdf/1311.0243
If you go read the original paper it is quite concerning. I have read some of it and as far as I understand there is a way for mining pool that are willing to cheat the system to get all the blocks at the expense of other pools. This trick is based on keeping the blocks that are found hidden, in other words when the cheating pool finds a block (solves the proof of work problem) it has a temporary advantage on other pools. This advantage can be exploited by looking to solve the p.o.w. for a second block without broadcasting the first one to the network. When the second one is found the other pools might have find an alternative first block which they can also broadcast but since the cheating pool is already ahead with two blocks, the other pools have wasted computing power for nothing and keep wasting computing power by considering a short branch of the blockchain. The regular pools find themself working on shorter branches than the one that will be broadcasted by the cheating pool. With careful adjustment of this strategy the cheating pool can mine more blocks that their hash rate could allow. This would make the cheating mining pool more profitable than the other pools. In this scenario the cheating mining pool would gain hash rate and increase at the expense of other pools (users would switch from less profitable pools to the cheating pool) . I do not know if this is something that can really be done and if Qubic has done this. If they did this and if this cheating system works then POW chains might have a problem. If this is a real threat to POW chains I would be expecting -80% in BTC price soon.
If you enjoy strategy, building and war games then you might enjoy this amazing game which is called Terracore. https://www.terracoregame.com/
