I have gaps in the images on my collection pages. The placement of gaps varies depending on how the collection is sorted - sometimes there are no gaps.
The theme is Redstorm and my shop is artivo.art.
Have another issue, too if you could help with it
In the collections sidebar a forward slash is above the title - on the product pages there are 2 slashes there.
Since this is a third-party theme, I couldn't say definitively. The issue may be the cause of a third-party app that is messing with the way your collection layout appears in various sorting settings. Otherwise, there may be something within the native theme code itself that is the culprit. I'd recommend reaching out to the developers for support.
With that said, I did try to replicate the issue on my own laptop and I did not come across the sorting issue. It's even possible it's a local issue with your device that is causing the website to format differently on your end. This is how it looked on my end:
If there is anything else I can help you with, please let me know.