Windows 11 24H2 26100.4652, Start11 2.53.
I've always used LaunchBar Commander to have a toolbar of buttons on the right (image 1).
After updating Start11 to version 2.53, the Launchbar expands to the entire right side (image 2).

I uninstalled Start11 and reinstalled it: the problem occurs when I enable "Let Start11 improve the taskbar" in the App Bar.
Now I leave the option disabled, but before the latest update, I used this option and the rounded edges of the taskbar, and LaunchBar worked fine.