I found an exploit...in 1 cave mission, some chests contain very valuable resources, such as upgrade modules and manipulator modules, while their extraction takes 2-3 minutes from the start of the mission. And by creating a flag in the cave, you can complete this mission many times and easily get a bunch of rare things.
I advise you to add all the rare items to the chest after the boss mission.
Sorry for my opinion about the balance of the game. I just know a lot of game mechanics and I want this modification to be as non-casual and balanced as possible.