In a lot of the back end settings where it is possible to set colours, the only option is to do this with a colour picker. I’m sure before it was possible to enter hex colours directly, which means you can get a correct colour match.
Not sure if this is a bug?
I hope you are well today and thank you for your question.
I have tested it on my test site and it’s working fine for me using latest version of Jevelin theme as displayed in the attached screenshot.
Please make sure you are using below latest version of theme and latest versions of plugins on your site.
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If you are still facing the issue then could you please share the screenshot of it so that i can troubleshoot it?