This Week in Plasma explains how we deal with post-release issues in the wake of Plasma 6.3—and how more testers are needed, and lists the UI improvements arriving in 6.3.1, and the new features lined up for 6.4.0. and beyond.
https://blogs.kde.org/2025/02/15/this-week-in-plasma-post-release-polishing/
There is a known bug about Wayland and ICC profiles in 6.3.