Where does kde-open5 look for root certificates?

After doing some testing and updates into Fedora 32, kde-open5 has now started behaving strange. Whenever I give it a https URL, it complains the verification of the server failed because the issuer certificate of a locally looked up certificate could not be found.

I’m then given the option to trust the certificate anyway, and the page will show up in Firefox as expected. So there is a click-through workaround, but I would of course like to fix this. (I would rather not reinstall this machine if it can be avoided.)

I’m sure this is something I have broken in my testing of Fedora 32 packages. But I don’t know where it went wrong. Any pointers or suggestions?