OP here. It’s been quite some time now but according to my notes the one thing that worked for me to eliminate the churn from kioslave5 was to un-install kdeconnect.
I took a subsequent note that removing the KDE comics widget from my desktop helped as well, as strange as that sounds.
Regarding your comment about Gwenview crashes, note that a recent update to the libexiv2 package broke Gwenview (among other applications). Make sure you have this version installed:
libexiv2-27:amd64 0.27.6-1ubuntu0.3
The version released earlier in the week last week definitely had something to do with kioslave5; see the bug report here (as suggested above by @meven):