How to fix apt update errors?

Hi, I was going to edit the source lists in /etc/apt/ or at least play with them to see if I broke it more or got anywhere, really learning the hard way here and could do with some input.

Below is the current state:

yogi@Distopia:~$ sudo apt update
[sudo] password for yogi:
Get:1 http://deb.debian.org/debian bullseye InRelease [146 kB]
Ign:2 http://security.debian.org/debian-security bullseye-updates InRelease
Get:4 http://deb.debian.org/debian bullseye-updates InRelease [40.1 kB]
Err:5 http://security.debian.org/debian-security bullseye-updates Release
404 Not Found [IP: 151.101.234.132 80]
Get:6 http://deb.debian.org/debian bullseye/main Sources.diff/Index [63.6 kB]
Err:3 https://dl.bintray.com/etcher/debian stable InRelease
403 Forbidden [IP: 52.43.14.61 443]
Get:7 http://deb.debian.org/debian bullseye/main amd64 Packages.diff/Index [63.6 kB]
Get:8 http://deb.debian.org/debian bullseye/main Sources T-2021-06-07-0205.53-F-2021-06-07-0205.53.pdiff [1,666 B]
Get:8 http://deb.debian.org/debian bullseye/main Sources T-2021-06-07-0205.53-F-2021-06-07-0205.53.pdiff [1,666 B]
Get:9 http://deb.debian.org/debian bullseye/main amd64 Packages T-2021-06-07-0205.53-F-2021-06-07-0205.53.pdiff [8,009 B]
Get:9 http://deb.debian.org/debian bullseye/main amd64 Packages T-2021-06-07-0205.53-F-2021-06-07-0205.53.pdiff [8,009 B]
Get:10 http://deb.debian.org/debian bullseye/main amd64 DEP-11 Metadata [4,016 kB]
Get:11 http://deb.debian.org/debian bullseye/main DEP-11 48x48 Icons [3,478 kB]
Get:12 http://deb.debian.org/debian bullseye/main DEP-11 64x64 Icons [7,305 kB]
Reading package lists... Done
E: The repository 'http://security.debian.org/debian-security bullseye-updates Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch https://deb.etcher.io/dists/stable/InRelease 403 Forbidden [IP: 52.43.14.61 443]
E: The repository 'https://deb.etcher.io stable InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

--- and current apt source.list file reads ---

# See https://wiki.debian.org/SourcesList for more information.
deb http://deb.debian.org/debian bullseye main
deb-src http://deb.debian.org/debian bullseye main

deb http://deb.debian.org/debian bullseye-updates main
deb-src http://deb.debian.org/debian bullseye-updates main

deb http://security.debian.org/debian-security/ bullseye-updates main
deb-src http://security.debian.org/debian-security/ bullseye-updates main

Poking around those url's I found the following path which is a little different to what's in the source list and to me looks like it could work from there? Total noob here, but would changing any of the deb-src lines with the below get me any further?

http://security.debian.org/debian-se...security/main/ The main change in it being ...debian-security/dists/bullseye-security...