$ grep -rnw '/etc/apt/' -e 'insync.io'
/etc/apt/sources.list.d/insync.list.save:1:deb http://apt.insync.io/ubuntu fossa non-free InRelease contrib
/etc/apt/sources.list.d/insync.list:1:deb http://apt.insync.io/ubuntu focal non-free contrib
/etc/apt/sources.list:58:deb-src http://apt.insync.io/ubuntu focal focal InRelease
/etc/apt/sources.list.save:58:deb-src http://apt.insync.io/ubuntu focal focal InRelease
PS: Sorry it took me so long to reply, and thank you SO much for the immense dedication in helping me!