IIRC it wasn't VCL but another framework like VCL that was built on Qt.

LCL (Lazarus' equivalent of VCL) took another approach where the base stuff are very Windows-y (due to the VCL heritage) but the backends have to essentially implement not only the backend-specific (Gtk, Qt, etc) widget functionality but also a small subset of the Windows API.

While this makes porting harder for the Lazarus developers, it makes it easier to port stuff between OSes and even port stuff from Delphi to Lazarus (some developers can also use both Delphi and Lazarus - e.g. AFAIK Total Commander uses Delphi for the 32bit builds and Lazarus for the 64bit builds).