Eevee Render: Objects disapearing in some frames

Hi again,

I am rendering an animation in Eevee and noticed something strange.

In some frames some objects disapear in one single frame and will be back in the next.

Even my rigged main character disapears sometimes for a single frame.
In Viewport mode this is not detected.

Does somebody know, what might be the cause of it and how can I stop it.