This also happens with Linux 2.90.0 version:
george@george-VirtualBox:~/blender$ ./blender -b -v
Blender 2.90.0 (hash 0330d1af29c0 built 2020-08-31 11:54:54)
Blender 2.90.0
build date: 2020-08-31
build time: 11:54:54
build commit date: 2020-08-31
build commit time: 11:26
build hash: 0330d1af29c0
build platform: Linux
build type: Release
build c flags: -Wall -Wcast-align -Werror=implicit-function-declaration -Werror=return-type -Werror=vla -Wstrict-prototypes -Wmissing-prototypes -Wno-char-subscripts -Wno-unknown-pragmas -Wpointer-arith -Wunused-parameter -Wwrite-strings -Wlogical-op -Wundef -Winit-self -Wmissing-include-dirs -Wno-div-by-zero -Wtype-limits -Wformat-signedness -Wrestrict -Wnonnull -Wabsolute-value -Wuninitialized -Wredundant-decls -Wshadow -Wno-error=unused-but-set-variable -Wimplicit-fallthrough=5 -fuse-ld=gold -std=gnu11 -msse -pipe -fPIC -funsigned-char -fno-strict-aliasing -msse2 -D_GLIBCXX_USE_CXX11_ABI=0
build c++ flags: -Wredundant-decls -Wall -Wno-invalid-offsetof -Wno-sign-compare -Wlogical-op -Winit-self -Wmissing-include-dirs -Wno-div-by-zero -Wtype-limits -Werror=return-type -Wno-char-subscripts -Wno-unknown-pragmas -Wpointer-arith -Wunused-parameter -Wwrite-strings -Wundef -Wformat-signedness -Wrestrict -Wuninitialized -Wundef -Wmissing-declarations -Wimplicit-fallthrough=5 -fuse-ld=gold -std=c++17 -msse -pipe -fPIC -funsigned-char -fno-strict-aliasing -msse2 -D_GLIBCXX_USE_CXX11_ABI=0
build link flags: -Wl,--version-script='/home/sources/buildbot-worker-linux_centos7/linux_290/blender.git/source/creator/blender.map'
build system: CMake
Error: Not freed memory blocks: 371, total unfreed memory 0.135937 MB