I would suggest posting a bug report upstream.
Then, I checked current bug issues and in one of them with a “Can’t click on Latte” problem, the Latte dev says:
I wont even look at it because Plasma is not really providing an official way to support screen scaling under X11. You can ask them if you want, the use of PLASMA_USE_QT_SCALING=1 is not advised and supported by Plasma team.
So for scaling related issues under x11 first Plasma should define which way is officially supported in order for Latte afterwards to follow.
Until then all scaling issues under x11 are considered irrelevant.
This confirms my perception of Plasma being on critical development phase.