Using Gimp 2.10.20

I am working on a project that is 747px by 1122px. For some reason, when I export as a PNG or JPG, the size bumps down by a pixel to 747pix by 1121px.

It needs be remarked that the text in the menu bar at the top of the screen reads 1121px, but I can assure you my working space has 1122px.

What on earth is happening. How can I export this at 1122px? tiff seems to work fine for maintaining 1122, but I need something that will only export visible layers. Help.

Have you tried starting with a pixel larger than you want?

I’m too far deep in my project

you realise you can make your canvas larger while you are in your project before you save it?
Image > canvas size.

Otherwise wait for someone else to answer your question.

Be sure to resize that layer to image size before export.