@Jan19871,
I'm not sure what the solution is if neither resetting to saved layout nor resetting preferences worked. It does sound like something is wrong, but I am not certain of that.
I want to be sure you are looking at the right info regarding Workspace vs Panel, and the difference between a Workspace being active vs any particular Panel being OPEN and being ACTIVE (in focus). (A "panel" can be open, and its tab will show in a panel group, but only one Panel in a panel group can be in focus at a time.)
I'll refer to this help page:
https://helpx.adobe.com/premiere-pro/using/workspaces.html
When you say "Color panel under Workspaces," I think you are talking about the "Color Workspace." (There is no Color "Panel.") Have you ever used the "Edit Workspaces"? If so, it is possible to hide the Color Workspace. But it would reappear when you Reset Preferences. (See the help page re "Modify the order of workspaces.")
If I go to the Editing Workspace, the Essential Graphics Panel is not open and is not displayed. But I can go to Window -> Essential Graphics Panel, and open it. If I then use Window -> Workspace -> Reset to Saved Layout, since I am in the Editing Workspace, it will reset to the saved layout - and remove the EGP. If I reopen the EGP and then switch to the Color Workspace, the Color Workspace does not include the EGP, so it is closed.
Also, be aware that if you have selected Window -> Workspaces -> Import Workspaces from Project this can affect what you see when you open a project.
Stan