I have a script I made that down-scales images and a bunch of other stuff on top of that. The important thing is that I can't make CV2 shut up about it. It seems to be specific to the terminal if it displays those messages or not. I use logging.getLogger(cv2.__name__).setLevel(logging.WARNING); to make it quiet. This works in Window(although it doesn't show these messages either way) & VSCode's integrated terminal but not in Gnome's terminal. Note that I use Fedora 36. I have no way to test this, but this needs to work on MacOS too.
The annoying messages:
[ INFO:0@0.840] global /builddir/build/BUILD/opencv-4.5.5/modules/core/src/parallel/registry_parallel.impl.hpp (96) ParallelBackendRegistry core(parallel): Enabled backends(2, sorted by priority): TBB(1000); OPENMP(990)
[ INFO:0@0.841] global /builddir/build/BUILD/opencv-4.5.5/modules/core/include/opencv2/core/parallel/backend/parallel_for.tbb.hpp (54) ParallelForBackend Initializing TBB parallel backend: TBB_INTERFACE_VERSION=11103
[ INFO:0@0.841] global /builddir/build/BUILD/opencv-4.5.5/modules/core/src/parallel/parallel.cpp (77) createParallelForAPI core(parallel): using backend: TBB (priority=1000)