You can try sending this raw/bypassing TMI.js in case TMI.js is interferring/internally validating and blocking hexcode colors and validating the colors against the known list
This thread did go rather sideways on that, since I acknowledged the use of tmi.js in the first reply, the 22 day gap threw me off
Being a TMI.js issue rather than a Chat issue, means it’s better suited on their support systems not here. The forum can’t easily support various libraries.