Yes, I agree, too.
Gnome-Extensions are great for what they do... But they are also all independently developed in resistance to Gnomes removal of features.
Not all extensions address something that Gnome Removed. Many are just helpful add-ons.
But none are supported or vetted by Gnome. And... an update from Gnome can break or render an extension useless, easily. Gnome does not take them into consideration, as Gnome considers them "niche hacks".
What is supposed to happen is installing the Dash To Dock will default to Dash, rather than the Ubuntu panel.
How to View and Change Advanced Settings of the Default Ubuntu Dock.
As Zorin OS is not Ubuntu, even if based on Ubuntu, this may not work properly. The same problem may exist on other distros, too.
And I looked.
And it does:
https://www.reddit.com/r/gnome/comments/p0sqrr/pop_os_2104_two_panels_when_using_dash_to_dock/
The common suggestion is the same I usually give: Disable ALL extensions, then enable dash to dock, then each extension after until the problem reappears (If it does not disappear when you disable all extensions except dash, then this is a moot point.)