Hello,
I have checked your website on GTmetrix and the serve scaled images means that you are using the images that are uploaded in bigger size and their use in the website is less than the actual size in which they were uploaded.
As you mentioned that you are using product images of 416×416 px.
I have logged into your website and saw that you are using a thumbnail width of 300px and the crop is set to 1:1.
Screenshot for Clarification: https://ibb.co/Brzd83C
Which clarifies that your actual image size is 416×416 px and you are using images width of 300×300 from settings as mentioned above. That’s why you are scoring low on serve scaled images.
Best Regards.