SUMMARY Windows that do not have transparency will not blur the title bar. OBSERVED RESULT KWin will not blur windows that do not have transparency. EXPECTED RESULT KWin blurs all windows or blurs windows that have transparency or a transparent title bar. SOFTWARE/OS VERSIONS Linux/KDE Plasma: 5.18.5-AMD-znver2 (available in About System) KDE Plasma Version: 5.25.0 KDE Frameworks Version: 5.95.0 Qt Version: 5.15.4 ADDITIONAL INFORMATION I use a transparent title bar theme that requires that windows always blur for it to look correct. AFAIK this is a regression since it only did this after upgrading to KDE 5.25.0.