Open the "Palettes" docker. You can get there through Window>Dockers>Palettes, or through Window>Color Palettes>Palettes.
If you have checked some "high level" checkbox - for example, "Palette Libraries" - then you have turned on visibility for all palettes that are under that checkbox.
Uncheck as necessary. Or, use Window>Color Palettes>Close All Palettes.
For some of these things, they can take so long that you may think that the program has gotten hung up.
I had that happen to me once, an entire screen.
That's something about 2019 that never made much sense to me.
It's cool with me if they want to use checkboxes instead of the "eye" icons - I prefer the checkboxes - but I don't see the benefit of having a checkbox for an entire branch of the tree.
Thank you very very much
Who cares what they use but having a screen filled!