After removing exif/meta data from an image, file size becomes larger.

After putting a photo into https://privmeta.com to remove the data from an image, I noticed that the file size is larger. Original file is 545 KB, the file I put through the website is 647 KB.

I looked at both photos, and there seems to be no difference. After close examination in a photo editor, I could not find any differences between the 2 images.

In the details tab for file explorer, everything is exactly the same (i guess the original image didnt have any exif/meta data to start with), Virustotal scan has no detections.

Does anybody know why this is happening?