Transition Problem: Slide with Gray Space

[Jhon16]

Hello everyone group, I have a little problem that has arisen.
It's strange how this issue surfaced, as no changes were made to the slides or anything. It's really strange.

As you can see from the video, when the slide changes it leaves a gray space, but this was not the case before. In the sense that before, when the other image passed, you began to glimpse the next image without creating space or gray backgrounds like that.

In your opinion, what could the problem be?

This is the link to my site: memoir-vintage.com

Thanks to everyone who will help me

P.S. : I forgot, I can only see this problem on tablets and Desktop PC devices, for mobile, I don't have any problems, it looks good