It must have something to do with Brief emulation. I can reproduce the problem with new configs:
1. Run 21.0.3 with a new config:
"c:\Program Files\SlickEdit Pro 21.0.3\win\vs.exe" -sc C:\Temp
2. In the setup wizard, select Brief emulation and leave everything else as default.
3. Change config option to use the search tool window rather than Mini.
4. Open a file and search for something. Make sure Match Case is disabled and Use regex is enabled.
5. Close 21.0.3
6. Run V22 RC1 and migrate the config:
"c:\Program Files\SlickEdit Pro 22.0.0\win\vs.exe" -sc C:\Temp
7. The same file should be open, so search for something. Notice Match Case is enabled and Use regex is disabled.
However, if I go through that same process but leave the emulation as CUA in the setup wizard, then the problem does not occur (step 7 has Match Case disabled and Use regex enabled as expected).