Qt platform plugin required for PyPlot

I have removed the .julia directory and used Pkg package manager to install PyPlot only in Julia 1.6.3 on a Windows machine. qt.qpa.plugin returns an error.

julia> versioninfo()
Julia Version 1.6.3
Commit ae8452a9e0 (2021-09-23 17:34 UTC)
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: Intel(R) Xeon(R) W-2123 CPU @ 3.60GHz
  LIBM: libopenlibm
  LLVM: libLLVM-11.0.1 (ORCJIT, skylake-avx512)

julia> using PyPlot

julia> plot([1,2,3])
qt.qpa.plugin: Could not load the Qt platform plugin "windows" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: direct2d, minimal, offscreen, windows, webgl.

(@v1.6) pkg> st
      Status `C:\Users\nmr\.julia\environments\v1.6\Project.toml`
  [d330b81b] PyPlot v2.10.0

The solution proposed in python - How to fix "could not find or load the Qt platform plugin windows" while using Matplotlib in PyCharm - Stack Overflow with QT_PLUGIN_PATH set to .julia\conda\3\Library\plugins does not seem to work.

Has anyone already seen it?