Portfolio project image not showing right

[nataliartpolo]

Hi guys!
A few months ago I published for the first time a couple of projects in the portfolio section here on Fiverr and for the first projects it is true that I did not follow the recommendations on the size of the images provided by the platform, so, as expected, the thumbnail of these projects did not look good. But as they were small projects I didn't give it too much importance.
A few days later, I published another project, this time more polished and following the image size recommendations for the cover, and I was very satisfied with the result. It's a project I'm proud of and I wanted it to look good.

The problem comes today, when I decided to publish another project in my portfolio, I followed the guidelines and the same steps I followed with the previous project, but this one, for some reason, doesn't look as expected. The image looks small with a blur around it that fiverr adds automatically for unknown reasons.
Both images of the last two projects are the same size (1024x768) and neither is larger than 50 MB (only a few kB). Both have backgrounds (i.e. no transparent background) and were exported as .png.
I have tried exporting the images from this last project in .jpg and the same thing happens. I have even tried publishing the project using another browser, and the problem persists.

Has anyone else had this happen, does anyone know how to fix it, is it even my problem or the platform's problem?

Edited 2 hours ago by nataliartpolo