The hook_uninstall removes svg from settings.file_extensions. In my opinion this should not be done. Either there is another module that supports svg images, through an implementation of ImageToolkit or overriding the ImageWidget, which would allow svg uploading, or there is no such override. If there is no override the allowed extensions are limited in the ImageWidget.
Remove the part in svg_image_uninstall that removes the extension from image fields.
Active
3.0
Code
I would generally agree with this, but we should be very careful with adjusting the hook_uninstall(), we don't want to get a regression and run in to this very major issue once again:
#2941795: Uninstalling module wipes out unrelated display configs. →
.
Did not dig deep enough, whether this is even fixable without causing a regression and in my opinion, it isn't worth it. But if anybody needs it, feel free to provide an MR!