Don't think it's that, as HDR is turned off on my own screens.
Interesting. The dark mode as well? Here Mica doesn't appear to like my HDR monitor at all.
I absolutely love this theme. I installed it the first day I started Directory Opus trial.
I set it as follows:
dopus.viewpiccontainer -> Default, Default, Default, Off, Off.
dopus.lister -> Dark, Mica, Default, On, Off.
In Windows 11 Settings -> Personalization -> Colors, option "Show accent color on title bars and windows borders" should be switched to Off.
I basically see no issues when using Optus, although I'm a newbie user, so maybe I didn't explore everything yet.
I wonder, if such a beautiful theme will be available on Opus 13? Maybe natively? Or will this one actually work? I'm thinking about buying Opus now, but I'm very sensitive when it comes to colors and themes, and once I got used to Mica, I wouldn't be able to change it to anything else 
You can try the public beta for free to see how it works.
(I still wouldnât personally recommend the Mica tool due to how it works with incorrect assumptions about the unused alpha channel data in other programsâ windows.)
Wow, thank you! I didn't know I could use the trial evaluation code to get the BETA cert.
After a quick luck, it also works great on Opus 13, with some very minor bugs, such as too-dark background in certain spots on the navigation bar. After installing BETA it was needed to re-apply this Mica theme, and then it became nearly as perfect as on Opus 12.
It's understandable that developers shouldn't recommend things that might bring up problems and potentially "false-positive" bug reports. However, I personally think that this Mica works very well. Maybe they improved it with the newest Mica For Everyone versions? I'd recommend to give it another try, because I'm very impressed with how beautiful it is.
Yes the UI is not readable when HDR is enabled