The symptom of this problem was first identified by a community user. I've most recently reproduced it with the GA Windows installer Brim-Setup-0.30.0.exe and the Zui Insiders installer Zui---Insiders-Setup-0.30.1-29.exe.

On all platforms, Brim and Zui Insiders maintain separate locations on the filesystem for data+config, which allow them to have separate lakes, separate settings, etc. They're supposed to also maintain separate locations for application binaries, and this is indeed true on macOS and Linux. The problem here is that on Windows they seem to share the same location under %USERPROFILE%\AppData\Local\Programs for application binaries. Here's repro steps to see what can happen.

1. Start with a "clean" Windows system that has no existing/prior Brim or Zui Insiders install.
2. Install Zui---Insiders-Setup-0.30.1-29.exe. At this point we see:

C:\>dir %USERPROFILE%\AppData\Local\Programs
 Volume in drive C has no label.
 Volume Serial Number is 0C07-A419

 Directory of C:\Users\Phil\AppData\Local\Programs

07/25/2022  10:36 AM    <DIR>          .
07/25/2022  10:36 AM    <DIR>          ..
01/20/2016  10:44 AM    <DIR>          Common
10/20/2021  03:35 PM    <DIR>          Python
07/25/2022  10:36 AM    <DIR>          zui-insiders
               0 File(s)              0 bytes
               5 Dir(s)  16,874,004,480 bytes free

C:\>%USERPROFILE%\AppData\Local\Programs\zui-insiders\resources\app.asar.unpacked\zdeps\zed.exe -version
Version: v1.2.0-11-gcd2f3a37

3. Quit Zui Insiders
4. Install Brim-Setup-0.30.0.exe. At this point the Zui Insiders launch icon disappears from the desktop and its entry is also gone from the installed Programs in Settings. A look at the filesystem shows that the binaries actually landed in the existing zui-insiders directory, proven by the fact that the zed.exe version went backwards to the one associated with the older GA Brim release.

C:\>dir %USERPROFILE%\AppData\Local\Programs
 Volume in drive C has no label.
 Volume Serial Number is 0C07-A419

 Directory of C:\Users\Phil\AppData\Local\Programs

07/25/2022  10:36 AM    <DIR>          .
07/25/2022  10:36 AM    <DIR>          ..
01/20/2016  10:44 AM    <DIR>          Common
10/20/2021  03:35 PM    <DIR>          Python
07/25/2022  10:39 AM    <DIR>          zui-insiders
               0 File(s)              0 bytes
               5 Dir(s)  16,879,833,088 bytes free

C:\>%USERPROFILE%\AppData\Local\Programs\zui-insiders\resources\app.asar.unpacked\zdeps\zed.exe -version
Version: v1.1.0

I've confirmed that neither macOS nor Linux seem to have this problem. When both apps are installed, they show separate "Brim" and "Zui - Insiders" filesystem paths for binaries.