Potential memory leakage in function definition using multiple threads in linux?

julia> versioninfo()
Julia Version 1.4.1
Commit 381693d3df* (2020-04-14 17:20 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i3-5005U CPU @ 2.00GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-8.0.1 (ORCJIT, broadwell)
Environment:
  JULIA_NUM_THREADS = 4

julia> @sync for i in 1:100
                  Threads.@spawn begin
                    function foo()
                      [fill(1.0, 2_00_000) for _ in 1:1000]
                      nothing
                    end
                    foo()
              end
              end

When i ran the above code which consumed 6.9G of ram (not the issue) after execution running GC.gc() multiple times only releases about (2.5G). I found a related github issue https://github.com/JuliaLang/julia/issues/30653 which appears to have been fixed. Is this a bug??