1 person found this helpful
check what you have set under FILE SETTINGS and IMAGE SIZING in the Export dialog. Those settings have an impact on file size.
You might also check this page in Adobes help pages: https://helpx.adobe.com/lightroom/help/exporting-photos-basic-workflow.html
Hope that helps.
It all depends on what type of image you started with, what type of image you are exporting to and what your setting are in the export dialog.
Without knowing all those factors it is hard to say why the file size is being reduced.
Did you actually LOOK at the exported photo? Does it look ok? Does it have the desired number of pixels (width and height)? If it looks ok and has the desired number of pixels, then it is ok.
The file size is a meaningless number, you can't compare file sizes from before and after. You are being misled by the file size comparison.