Updated #postmarketos to 26.06 on my librem5. Now red and blue colors are swapped. 
More interestingly, they are correct during entering FDE password and on login screen (I use plasma desktop).
@etam There were recent changes in Mesa by @austriancoder that sound like they could be related: https://christian-gmeiner.info/2026-06-10-fixing-the-rb-swap-the-right-way/
Worth checking whether all of these fixes are present in the version used in this pmOS release.
@janvlug @austriancoder @etam Nope. This was an ancient GTK3 issue.