Redesign UX, UI in the panel

Maybe some webdesigner would look at it?
Boei has different functionalities but lacks a professional appearance.

For example, see:
https://www.flowlu.com/
https://www.tabextend.com/

P.S.
What would I change for sure:
• Left menu
• Dark mode
• Customizable dashboard (to decide what is displayed on it)
• List by customers e.t.c.

@Jack S.: Thanks for the clarification.
I appreciate your opinion, but I think this is more a personal preference.
Because my opinion:

• left menu -> I like it more at the top, maybe if it becomes bigger it can go to the left
• dark mode -> this is not a must have for me
• customizable dashboard -> makes sense, but this is a feature on its own, in the future we can add something like this
• list of customers -> I don't understand which customers, we list buttons?

Ruben