Single product images displayed incorrectly

Good evening, for days I have been looking for an answer and I do tests but nothing!
I just “finished” a wordpress ecommerce site (5.5.3) with woocommerce (4.7.1) and the EightStore Lite theme (1.2.4), below you can see the installed plugins.

In the single product page I have 2 images, the main one (white background) and one in the gallery (brown background), then under the main image (opened) there are the two clickable thumbnails. Upon clicking on one of these, the large version is shown. In turn, if you pass on the image just opened, I will have the zoom of the detail correctly. In short, the classic system.

The problem is that, apparently with random frequency but very frequently, the second image (therefore not the main one), when selected (click on the thumbnail) is shown completely without detail, as if a very small version of the image were loaded and “stretched ” to cover a larger area.
If in this situation I step on the large image (the undefined one), the zoom works and I see sharp details but as soon as I leave the image area, it becomes degraded again.
Finally, if I click on the magnifying glass at the top right, the image is opened correctly in full screen.

Sometimes, the same problem occurs directly when opening the page also for the main image (white background). Normally with one or more page “hard refresh” [ctrl + F5], the images appear right.

I am puzzled by the fact that it seems to happen without logic, initially only noticed on smartphones, now I have realized that it also happens on desktop.

Anyone have any idea how to help me? What should I go to change? I get by with html, css and I understand a bit of js but this time I’m in trouble. Could it be a cache problem? But I tried to clean both the browser one and the one with autoptimize and switch browsers to one that had never opened the page… and nothing.

Thanks a lot to anyone who wants to help me!
– Fabio

Screenshot of the problem:
https://www.bassottocreativo.it/problema-img-prodotto/example-problema.jpg
Plugin List:
https://www.bassottocreativo.it/problema-img-prodotto/Lista-plugin-attivi.pdf