I finally found time for this. Here are some changes:

• Image, gif and video extensions will no longer be changed, they will remain as they are.
• File quality will not be reduced, they will remain at max quality.
• Added support for types such as APNG, JPEG-XL.
• Animation types will not be converted to video.
• The file size limit remains at 20mb. If I can somehow solve the donation issue, I would like to increase this limit in the future.

Thanks to @asonix for making the above and many more improvements.

Please let me know if you encounter any errors. I need to tweak the configurations a bit more I guess.