Reading package lists… DoneN: Skipping acquire of configured file ‘main/binary-i386/Packages’ as repository ‘http://apt.postgresql.org/pub/repos/apt focal-pgdg InRelease’ doesn’t support architecture ‘i386’
Replace the line in the file /etc/apt/sources.list.d/pgdg.list with
deb [arch=amd64] http://apt.postgresql.org/pub/repos/apt/ focal-pgdg main