The most important change for me in Plasma 5.27.2 is that the following issue is resolved:
My Manjaro broke for some reason (Plasma GUI)
Panel icons disappears after hovering
All desktop and menu icons missing
Icons missing, wrong fonts, unresponsive plasma after update
I personally found the culprit and reported it to the KDE team.
Additionally, a related bug with the external monitor on NVIDIA was fixed.