Issues with Big Sur? Apple is having/has had issues with app and certificate notarising with the launch
I don't know if some of you were already onto this, but this Wired.com article might explain some of the hiccups currently rampaging across a lot of Mac users.
Apparently there are/were some back-end issues at Apple with apps timing out while trying to notarise apps and certificates. The article makes it seem like it's over now, but who knows. If troubles start up again you might want to check the error console to see if it's the same issue.