For me the problem is that the exported video from Premiere looks less sharp less clear and with more white color or maybe even noise and less vibrance/saturation that the original one. It also looks a bit foggy so to speak.
My original videos comes from canon eos the video format is .mov, framerate is 25 and the resolution is a full HD: 1920*1080. For the output:
h.264
Full HD
25 fps
profile:High
level:5.2
birthrate: 100 Mbps (source file is around 45 Mbps)