Hi @weltenraum,
With so little info is difficult to say what’s going on. Try doing some basic debugging:
Does this issue happen with a different theme as well? (Eg. Twenty Twenty)
Does this issue still happen with all other plugins deactivated? (except for WPP of course.)
Which plugin version are you using over there?
Please start with that and come back once you’ve gathered some more information.
Edit: Please scratch all that. I’m guessing that by “theme” you mean the Kappa theme. If so, please get in touch with its developer and ask them to look into it for you. They need to update their theme’s code.