Well, they all kind of have pseudo cliff hangers, depending on how you look at it... for a couple of examples:
Civil war was kind of a cliff hanger... but at the same time it was setting up for the next movie, so it ended precisely where it needed to (although, I was still a little dissatisfied with this one too).
guardians of the galaxy ended with the unresolved issue of peter's heritage being half human half something else powerful. That's not really important for wrapping up that movie's story, and plays into its sequel setup too
They all resolve the stories they're focused on... but there's the grander story everything is leading up to. The different infinity stones are the focus of the respective movies they were featured in, but thanos is behind most of the conflicts; the puppet master ultimately trying to get his hands on the stones. Eventually they're all going to crossover to finish that grander story.
THAT is world building and it works in a very effective way. Each of the movies are connected and telling a grander story. Eventually that grander story will conclude, but you can still watch them solo and feel satisfied with the smaller story being told in that one movie.
What covenant did, was a total setup for the next movie, but unlike the marvel movies it only has one story tier, and the movie didn't wrap up in a satisfying way (to me), so it had to end on a cliff hanger to leave room for that next planned sequel...
