Are you really using Windows XP ? Not that it is a problem.
What version of Gimp were you using and I will get you a download link. Otherwise you have to go here: https://download.gimp.org/mirror/pub/gimp/ and trawl through the various versions.
One snag is installing an old version will / might uninstall your Gimp 2.10 It would be better to determine what is wrong with the newer images
If you have an old (workable with Canva) image you can share, then there are tools such as command line ImageMagick which can determine the file properties.
Edit: Just a thought. What determines your image size? Gimp 2.10 now defaults to 300 ppi (used to be 72) so if you set canvas size by inches the file size is that much larger.
What version of Gimp were you using and I will get you a download link. Otherwise you have to go here: https://download.gimp.org/mirror/pub/gimp/ and trawl through the various versions.
One snag is installing an old version will / might uninstall your Gimp 2.10 It would be better to determine what is wrong with the newer images
If you have an old (workable with Canva) image you can share, then there are tools such as command line ImageMagick which can determine the file properties.
Edit: Just a thought. What determines your image size? Gimp 2.10 now defaults to 300 ppi (used to be 72) so if you set canvas size by inches the file size is that much larger.