The registry key is currently WoW shared in Wine if there is no WOW6432Node subkey. This is not the case on Windows, the key is present from somewhere at least on my install and can be created (as included test suggests). That stops sharing of HKCU/Software in Wine and breaks a lot of things. [1] lists, in particular, HKCU/Software as shared and the test confirms that.
This fixes Ubisoft login under Steam (and some other accompanying failures resulting from weirdly working registry) for some games (like Far Cry 3) which happen to create HKCU/Software/WOW6432Node key during their setup steps.
1. https://learn.microsoft.com/en-us/windows/win32/winprog64/shared-registry-ke...