For a long time, the holy grail of front-end developers was “pixel perfect designs.”
Mobile destroyed that.
The range of devices the things we build will be viewed and used on is huge. Things will never look exactly the same from one device or viewport to the next.
Sometimes, designs come back with things that are, frankly, inaccessible or bad for users. It’s your professional obligation as a developer to point that out to the designer and push back.
Identifying those issues isn’t something you’ll always be able to do (or do well) earlier in your career. It comes with experience. Pointing them, and, more importantly, making suggestions on how to address them, is even harder, and comes with even more experience.
Don’t feel bad if you can’t do that yet. It’s something to work towards.