So, this is something I’ve had an issue with too in a number of setups/configs with many different led strips and controller boards and relays. I think I discovered a solution last night.
I noticed that on hard power on/off the strip was flashing the primary foreground color selected. Regardless if I chose a different pallette like Aurora, the strip was flashing orange when I powered it up and turned it off. I changed the foreground color on the preset to black and that fixed it across the board.
For recap - set an effect and color palette and set all unused foreground/background colors to black. Save the preset. Unplug and then plug back in and the initial color flash should be gone.
This problem baffled me for a long time. No recommendations have ever solved this issue aside from what I described above. Somehow that color selection is being passed to the strip even through a default preset, relay and level shifter.