Never use KF5
Index: shell_integration/CMakeLists.txt
--- shell_integration/CMakeLists.txt.orig
+++ shell_integration/CMakeLists.txt
@@ -11,7 +11,6 @@ if( UNIX AND NOT APPLE )
   endif()
 
   if(BUILD_SHELL_INTEGRATION_DOLPHIN)
-    find_package(KF5KIO "5.16" CONFIG QUIET)
     find_package(KF6KIO "5.240" CONFIG QUIET)
     if(KF5KIO_FOUND OR KF6KIO_FOUND)
       add_subdirectory(dolphin)
