So, one or more of the following is probably true:
OP downloaded a wrong file,
there was an error in downloading,
OP does not know how to properly calculate sha512sum
Try to download both endeavouros-2020.09.20-x86_64.iso and endeavouros-2020.09.20-x86_64.iso.sha512 again. Then run the following in the terminal (in the directory where you saved the two files):
I am using both the Windows built in version and some third party software and they both produce the same hash.
I downloaded the ISO from github.
Both on Windows and on the third party software I selected the sha512sum
Oh maybe I am not doing that method then. What I did was I selected the file and generated a hash and then I compared it to the file. it shoed different but yeah I will try this method.
Oh strange, for some reason yesterday I was getting the older version when I clicked on the github link. I guess the github link was not updated, today I am getting the latest ISO