Please tell us some basic information before asking for help:
Model Name: Zenfone 9
Firmware Version: WW.32.2050.2050.34
Rooted or not: Not Root
Frequency of Occurrence: Very Frequenc
APP Name & APP Version (If your issue relates to the app): Splendid
In addition to information above, please also provide as much details as you can, e.g., using scenario, what troubleshooting you've already done, screenshot, etc.
As far as I know in Splendid the Standard mode is sRGB and Optimal mode is wide color gamut (DCI P3).
I set Optimal mode in Splendid to get wide color gamut, but when playing HDR video in Youtube the color changing to Standard (sRGB) mode, if I close/stop HDR video the color back to Optimal mode.
I have Zenfone5 so I tried the same way too, the result is ok, it's still in wide color gamut.
Please fix this issue, thanks.