It's being made by a different studio, a smaller one that took 2 years to release Battlechasers Nightwars in 2017. It makes more sense that this was developed after the release of that compare to developing something else for a year then switching to this after DS:3(after it flopped for some reason) and trying to get a game out within a year.Possibly.
Though I wouldn't say that one minute trailer convinced me this has had years of dev time. It looks noticeably lower budget than Darksiders 3.