I think another reply mentioned that we still have the demon kingdom plot (cooperation with human kingdom, dealing with the old hag) and the story deal with enemy one by one. Spending actual 20 years to focus on the king alone, while many things happen in the background just doesn’t feel right. Neither is having Raoul flashback through other things he did in the 20 years.
for anyone that's like "this manga lost its plot" or "this is turning into nonsense" either forgot or wasn't paying attention or just doesn't get the concept, like his whole thing is getting revenge on anyone that had a part in it and a couple of chapters ago he realized the gods had a chance to help him but instead mocked him when they the ones made him into the hero anyway so he's getting revenge on everyone gods/towns people ( cuz they rejoiced at his death)/royalty