You probably know all of this but here it is anyway. This is a personal question, a desktop is good if you like it. If you want to play with it, you can try different themes, colors, icons, moving the panel from one side to the other, make it float or rounded, give a chance to a global menu, hot corners, Yakuake, different menus, fonts (Nerd fonts are fun BTW)...

I personally like minimal setups with powerful capabilities. I use Plasma too, but I use shortcuts all the time. That means, for example that I don't use a dock, I use Meta+W (or bottom corners) so I don't need it at all. Also, no widgets at the desktops (excets for sometimes notes) and only the ones I use at the top bar. Here is my setup if you want to check it out.

If you ask me, I think your desktop looks good, maybe I would make the top panel thinner to be more coherent with the bottom one. If it's Latte, I would make it get bigger with the mouse. About the apps, I don't trust Vivaldi or Mega, but I do trust Firefox and Nextcloud. But again, it's a personal decision.

PS: great film BTW