I would like to report an issue similar to BUG 234132. I was running FreeBSD stable 12 build r341835. My install included xserver 1.20 and mesa 18.3.1, with the drm-kmod for FreeBSD 12 (based on Linux KPI 4.16), using Haswell HD 4600 integrated video. I am also using the Intel driver, not modesetting. I was using Plasma 5.12.7, KF5 5.52 and QT5 5.11. Everything in Plasma was working fine, all of the KDE apps ran correctly and I had no issues.
When I upgraded to KF5 5.53 and QT5 5.12, I ran into very similar issues to what was reported from BUG 234132. There were rendering and screen flickering issues. My KDE desktop was virtually unusable from those issues. So first I uninstalled and reinstalled all of my apps from my poudriere repo and cleared the .cache folders in my accounts that I log into. The issue remained. I then downgraded my versions of xserver back to 1.18 and mesa back to 18.1.9 (essentially using the current ports tree) with a clean repo from poudriere. With Plasma versions 5.12.7, KF5 5.53 and QT5 5.12, the issues remained unchanged. I then reverted the updates for QT5 5.12 and KF5 5.53 back to QT5 5.11 and KF5 5.52, and cleaned out the .cache folders again, and rebuilt with a clean poudriere repo and the issue is gone. So I am essentially using the ports tree from right before the QT5 5.12 and KF5 5.53 commits were made. Everything is running normally and all of the KDE programs are running fine. I'm sorry for the lengthily post. I hope this can shed a little more light on the issue.
