problems I can not deal with in Big Sur

finally, saying hey from Big Sur.

but there's problems I don't know how to deal with!!

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1 - sound not working

2 - there is a black space in my screen

3 - I can not mount efi folder

like I can not access efi folder

first boot there was a hard disk icon I clicked it and mounted it but I can not find the efi folder anywhere !!!

as you see here I don't see any icons for hard disk