From what I can tell the conflict goes like this: The reward pool used to reward every poster and curator is limited each day. A couple whales (users with a lot of Steem Power) have enough power to claim a large percentage of this reward pool if they vote regularly each day. That results in fewer rewards for everyone else when used to a certain extend.

The user haejin posts up to 10 crypto market analyst posts a day and the upvotes on those posts make up a noticeable amount of the whole reward pool each day. The most value from those posts is added by haejin himself as well as another whale called ranchorelaxo, who mostly interacts with haejins posts on this platform. Bernie criticizes that and claims that haejin's posts are not worth the large amount of reward he receives from them. From there it's mostly a flag war going on, where Bernie flags haejins posts to reduce the payouts and haejin does the same to Bernies posts. There are also some personal insults exchanged between the two.