How do I fix color changes in Calendar app when using Hex or RGB codes?

I am trying to set some custom colors for my calendars and I am noticing that on a few different colors that I set they will get changed to something different. Not entirely different mind you, just something similar, maybe not as vibrant or just slightly off from the color I originally set. It happens immediately after I exit the calendar edit screen and go back to the list of calendars I want to display. For example I am trying to set all my birthday calendars from my various jobs and areas of life to a vibrant orange. The hex I’m using is FF8000 but as soon as I leave the screen where I’m editing any one specific calendar with that hex code it automatically and immediately changes back to EF8733. I have also tried using RGB values and the same thing happened. I set it at R255 G128 B0 and it came back as R239 G135 B51 as soon as I went back to the calendar selection screen. Does anyone know what is going on here, or is having similar issues? I would be fine with the orange it keeps going to but when you view your calendar in month mode it shows up as a sort of brownish color in the each of the smaller day squares that make up the month. Any help anyone can provide would be greatly appreciated, thank you! :)

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