Hello,
The issue happens for products with at least 6 images in the gallery, as you can see in the video bellow:
https://drive.google.com/file/d/1VDy_h28se3wT3vHtEHmkBAVgmxGhr-Ub/view?usp=sharing
Here is an example product:
https://coshop.ro/product/barca-gonflabila-pentru-cinci-persoane-cu-vasle-intex-excursion-5-gri-365x168x43-cm/