When importing jpg or png files, when exporting (or viewing in the monitor with color management off), there is a significant gamma shift.

In the image supplied, the top half shows what the original image looked like, with the text on the left showing the color values of each bar, and the bottom half shows what happens to the image after it's exported through Premiere (since v13), with the red text on the right showing the color values of the modified image in contrast.