Image Popup Size not correct

Opencart version 3.0.2.0
Extensions > Default Store Theme
I adjusted Product Image Popup Size (W x H) = 800x550.
So I prepared all my images to be 800px wide or 550px high, depending on their proportions.

Alas, when the popup is open, the images are a bit blurry and when you right-click on the popup and open image in a new tab then you see the real size perfect photo. So, the popup window shrinks the image with 1-2% and it is fatal.
What is the real size of the Popup window?
Why it doesn't apply the adjusted parameters?

Link to the site: https://philarooms.com/

Using a custom theme. Revert to the default theme and see if the same issue can be reproduced.

I use the default theme. I don't have other theme.

The default theme should be modified. Until you re-added the real, original and delivered theme from the OC ZIP file of opencart,com , you will not be able to compare the results with the issue you are reporting about.