I just realized that Bullseye also has mate-panel 1.24.1-1. But I don't see the compression problem with my Bullseye VM, just with the systems that are running Bookworm.
Also, on my Bookwork VM, if I tell the applet to display the workspaces in 2 rows, they have the correct dimensions. If I go back to displaying the workspaces in 1 row, they go back to being taller than wide. regards, mike