So this is not a blockbuster, no feature of well known actors, I’m afraid, too.
And I’m not entirely sure if it’s one or two movies, I remember two scenes, might be from different films, if so I’m willing to watch both.
First scene: post-apocalyptic scenario, abandoned building, people wearing old dirty clothes, hiding. There are troops that are hunting for them. Those poor people are hiding something - they’re gathering some ‘parts’ of some devices, making plans. These device - when build - will be used to fight in the future action.
Second scene - this is a spoiler, actually. In this movie (this might be scene from another movie, I don’t remember) there are two groups of warriors, soldiers. The first one we are looking wear some special helmets - they are told the helmets are protecting their brains from ‘aliens’. But - we know it at the end, there are no aliens at all - the helmets make people think their enemies are aliens, but in fact they are humans, too. When they take off helmets - they see that are fighting with other people, too.
The movie(s) is from 2010-2020 probably. Thank you and sorry for my English.