Hey! Oh man. It's crazy how specific they can be with passport photos. I had mine rejected once because there was a slight shadow on the background—no joke, just a tiny shadow from the lighting! I’ve learned since then that it’s all about following the official guidelines as closely as possible. For example, the background must be a completely plain white, with no variations or textures allowed. They’re also super picky about facial expressions—you're supposed to have a neutral expression without smiling, and definitely no "posed" looks.
If you're looking for a hassle-free solution, I recommend checking out
photogov.net. They provide clear guidelines and even offer a service for passport photos that meet all the requirements, ensuring you won't run into any issues!