I do not know why, but when the styles are declared as settings of the
BlockEditorProvider, then typing anything is too slow to be usable.
But, when the styles are declared within the BlockEditor, without the
useSelect hook, then it works as expected (not fast, not that, but at
least not intolerably slow.)
I tried with a useMemo to keep the styles the same when there is no
change, which is most of the time, but the behaviour is the same.
Since i do not need to pass the styles from without the application,
at least not for now, my only option is to have them directly in
BlockEditor.