UbuntuStudio 22.04 uses the Firefox Snap package by default. The latest automatic update does not display pages correctly in normal mode, but does work correctly on Safe Mode. Snap.io lists only the latest version of Firefox so I was unable to ask snap to revert to the previous release (prior to 5 Mar 24) and by the time I had tried to investigate the previous version was no longer cached. I did not see a way to force a fresh download of firefox from the latest channel on snap.io. I tried the snap beta channel for v124, but that exhibited the same problems. I tried adding a symbolic link to colors.css after seeing firefox complaining that it could not be found when started from the command line. That removed the error/warning message but did not clear the problem with normal mode. I use the en-GB locale extension only. The technical details about my PC are as follows: * Operating System: Ubuntu Studio 22.04 * KDE Plasma Version: 5.24.7 * KDE Frameworks Version: 5.92.0 * Qt Version: 5.15.3 * Kernel Version: 6.5.0-25-lowlatency (64-bit) * Graphics Platform: X11 * Processors: 12 × AMD Ryzen 5 7600 6-Core Processor * Memory: 30.5 GiB of RAM * Graphics Processor: RAPHAEL_MENDOCINO I have now downloaded v123 and installed it in my local home directory, and that version is working well. I have removed the firefox channel via snap. It is likely to be a fault in the construction of the snap for v123 that was not present for v122 prior to 5 Mar 24.