Hello everyone in this amazing community of designers. 
I see that the quality of the item display covers for the Elementor > template kits category is not sharp enough as the wordpress theme display images. For fast loading of the item pages, we always send them in .jpg format (with the image compressed on sites like (tinyjpg.com or compressjpeg.com).
The quality of the compressed images on these sites is almost unnoticeable.
When using .png images for the display of the covers, we notice that there is not much difference to png, although in this format the image size triples in many cases, this format is not very suitable for this.
I don’t know if Envato compresses the image even more for the item cover display, or if there is some other way that I don’t know of for a clear visualization of the items in the template kit category.
As for the display of the items in Envato Elements, the image display of the items is perfect, without squares and blurs.
It is an interesting subject to discuss as we know that the quality of the item display needs to be perfect in order to have more sales, as this is the gateway to know if the user will buy your item or not.
We would be very happy to hear your opinions, tips and ideas, which make this community so amazing.
Cheers!