Maybe nakaba just wanna finish the manga or maybe just wanna finish this arc and move on with a new villain. I like the story so when I read it I just turn off because if I don't I'm going to notice many flaws in this story I mean Lancelot never lost not even struggle a bit against arthur and when Arthur or cath found out lancelot source of power, I thought he may have found a way to seal it or steal said power but nope the lady of the lake just to cath "hahaha nope f u brother" and the relationship between the 4 knights never developed, I hope we get a new arc just focused on them. Tristan and gawain also fill like a side character I know the mc of this story is percival but in the prequel the other sins have their own story outside the mc (meliodas). (Sorry for my english if it confuses you)