Dear @wosinekp ,
Thanks for your patience.
Please, note that we still recommend disabling the pre-loader, as it will not only create issues on your website, but also have a negative impact on the website speed. Your theme support should be able to help with the deactivation, as pre-loaders are mostly an option from the theme if not added manually via a plugin.
We have checked all your websites. Let me go over each website separately.
https://kosciol.czest.pl/ website has both Cloudflare and hosting cache enabled, which makes it impossible for us to clear the website cache and troubleshoot. Will you please temporarily disable hosting cache and enable Cloudflare plugin, so that we can flush the website cache?
For https://dream-apps.pl/ website, please, clear your hosting cache and you should not face the issue anymore. However as mentioned above this change will have a negative impact on your website speed.
The issues on https://snyiwizje.pl/ website should be solved.
I was not able to reproduce the issue with images on https://kchwcz-worship.czest.pl/ website. Will you please provide us with a recording so that we can reproduce the issue and check further?
Regards, Mane