In PhpStorm's tip of the day or in older version of PhpStorm we can see current Inline Parameter Name Hint coloured highlighting:
But now in version 2019.3 i don't see coloured highlighting:
Is this a bug, a feature or did i miss something? Is somebody facing the same issue?
The problem was in themes switching.
After i updated to 2019.3 i installed theme Gruvbox Theme.
I didn't like it and switched back to Darcula.
But after that the PHPStorm internal color scheme config (.icls) still had traces of the uninstalled Gruvbox Theme.
Fixed it by installing another theme (Material Theme UI), and all is good now!