When you create an FX channel through a Channel's "Sends" menu, the new channel has the color of the channel you created it from.
Except that it doesn't....
In this freshly created FX channel, the channel color is pink, but if you look at the slider it is actually at a different value.
When you reload the project later, the channel color will have changed:
The color helps to organize my tracks/FX channels, so this is a bit of an annoyance.
Screenshots: https://imgur.com/a/zQEns1X
FL Studio Mobile 4.9.1 i on an iPad Pro