Ubuntu 24.04 desktop environments

[sofasurfer]

I wanted to try a different environment. I logged out and then clicked on my account. I clicked on the gear on the lower right. Isn't this where the installed desktop environments are listed? I chose "cinnamon" and tried it out. I then switched to "Ubuntu". I was expecting "Gnome to be listed but only "cinnamon" and "ubuntu" were there. Anyway, when I clicked "Ubuntu" I got my old desktop back but there was a difference. My side panel icons had changed. For instance the folder icon WAS a folder but now it is a file cabinet. The trash can is different too. What did I change?
$ echo $XDG_CURRENT_DESKTOP shows that I do have gnome.

 

[Condobloke]

I hope you have a Timeshift snapshot taken prior to starting your experiment.

 

[sofasurfer]

I do have backups. And I have a duplicate of my system on another disk. I just now went into the duplicate and did the same thing. When I clicked on the gear there were options for cinnanom and ubuntu. Ubuntu was checked. So I checked cinnamon and restarted. Indeed, cinnamon was active. I then went back and checked Ubuntu just as it was. When I rebooted my left panel icons were different.and all my folder icons are different.