I just installed the latest Nik collection update. I clicked the installer. A few windows later got a messsge that I needed to uninstall the previous version with the uninstalled. Did that. Ran the installer again. And ./.
All my applications, apart from the pre-installed ones, had been deleted!!
Luckily I had a very recent backup, but I will be very cautious with DxO updates in future!!
MacBook Pro 2019, Catalina