mass effect andromeda lighting and shadows pc version issue

The brightening/darkening that happens when you go into a dark or a bright space is caused by adaptation - it's the same thing that happens to our eyes when we go outside or into a dark room, it takes a few seconds for our eyes to adjust and until then some things will be too dark or too bright. A game's lighting can never properly replicate how our eyes work, and so there will always be times when it's too heavy-handed, not quick enough, too annoying, and doesn't quite work correctly.

That's one of the things that's probably going on here. The other is that in some places the ambient lighting is set for the tone of the area you're in, but individual characters haven't had any point lighting applied to them, or has inadequate point lighting. This is always going to be more of a problem with large games that have a huge cast of incidental characters. It doesn't mean there's a problem with your game, or that there's a bug in the game, just that the lighting setup was done in a particular way that doesn't meet the needs of every situation.