Hi Tristan,

This behavior is applied on purpose. 

When a control with text color markup capabilities is not focused, it will simply apply the dark-mode styling. The background will be made dark and uncolored text will be made white.

However, it is possible to display colored text and colored text background using this control.

Applying dark mode settings may render some explicitly colored text unreadable. This is the main reason we show the data as-is while editing, to clearly indicate the stored text was explicitly colored, on purpose.

Additionally, the colored text is often used in other scenarios, such as e-mails and reports and such. Not applying dark mode wile editing clearly shows show what the text will look like when embedded.