Enable dark mode in system preferences.
Add an action to a trigger, choose ""Insert / Type / Paste Custom Text"'.
Type into the text box.
The text will be white on a white background.
Thanks for this quick answer Andreas. Yes, you are correct. It it will stay black if we go back later to edit the same Custom text. However, if we create a second action (e. g. I am creating at the moment many Key Sequence → [Transform to] Custom Text in a row), text color will be at first white and will need to be change in order to be read while we type.
Let be clear: this is a simple annoyance and not a major "OMG It breaks everything" bug. But I preferred to let you know as it might be more troublesome for some users and it might shed light on others Dark mode related bugs
Maxime
P.S. Credits to Robert who noticed the bug is in Dark Mode.
These are hard to handle because what if you want to (for example) paste white text? Should it still show as black while in light mode? Unfortunately I think every option is in some way confusing ;-(.
I've also been experiencing this (minor annoyance) for years. Unless I'm missing something, given that the background color of the text field in that action doesn’t change once one is in dark mode, I would say the text color should not change either. Which is to say it should stay black by default, imo. (The edge case of white text being invisible in the field applies when in light mode too.)