Hey, it seems that there's an error in how the 4.6 → 4.8 migration script handles transparency. In 4.6, 20% transparency means a 80% alpha channel, while in 4.8 a 20% opacity means a 20% alpha channel. Meaning a 100% transparency on 4.6 is a completely transparent panel while a 100% opacity on 4.8 means a completely opaque panel. This is clear (no pun intended) in both interfaces, but having a 20% transparent panel in 4.6 leads to a 20% opaque panel in 4.8 so there's obviously something fishy.
Created attachment 3632 fix transparency -> opacity migration Here's an untested patch trying to fix the confusion between transparency (4.6) and opacity (4.8).
True, applied in 3603b4f.