That's another dark pattern that some sites use (used?), making the process of "storing your cookie preferences" take a long time - you see a spinner for a long time, while the 'accept and dismiss' button stays active and available throughout.

It should be illegal. Not accepting cookies is the default and should be a no-op. Accepting cookies is the one that should take a while, since only then do all the 3rd party scripts load in and do their thing.