Has there been any concern about privacy or tracking on Ubuntu, like there is on Windows 10.
Ubuntu includes telemetry which is sent back to Canonical. (Can be turned off), There was also a bit of a tiff in regards to it's online search results.
Win10's telemetry can be disabled via registry editor by adding an "AllowTelemetry" DWORD value to the key HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\DataCollection and setting it to 1, or by straight-up disabling the services responsible.