Main Images shown small

Recently, I launched a new product and we uploaded high resolution images of our product on Amazon but we noticed that our main images (all 7 of them) were shown quite small as compared to our competitors. We have another product whose images are of same resolution but are shown big (like we expect). We are confused why this is happening. Seller central support was not helpful in this matter.

Our images of 2500x2500 resolution.
Can somebody share their experience what helped?

Our issue is very similar to the issue mentioned in the other thread:

If we check the HTML of our product images, then we see style="max-width: 402px; max-height: 402px;
whereas when we see our competitor, his width and height are 600+px.

If you need more information, then please feel free to ask.