When I use sudo apt update these what I get as an output, multiple error tried to find answer but couldn't get any as working. Really new in the Linux field if you could help me out it will truly appreciated.
System Details: Description: Ubuntu 23.10 Release: 23.10 Codename: mantic
Err:2 https://brave-browser-apt-release.s3.brave.com stable InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 0686B78420038257
Err:6 https://ppa.launchpadcontent.net/nilarimogard/webupd8/ubuntu mantic Release
404 Not Found [IP: 185.125.190.80 443]
Err:8 http://download.opensuse.org/repositories/home:/manuelschneid3r/xUbuntu_23.10 InRelease
The following signatures were invalid: EXPKEYSIG 1488EB46E192A257 home:manuelschneid3r OBS Project <home:manuelschneid3r@build.opensuse.org>
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://brave-browser-apt-release.s3.brave.com stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 0686B78420038257
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.
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://download.opensuse.org/repositories/home:/manuelschneid3r/xUbuntu_23.10 InRelease: The following signatures were invalid: EXPKEYSIG 1488EB46E192A257 home:manuelschneid3r OBS Project <home:manuelschneid3r@build.opensuse.org>
W: GPG error: http://download.opensuse.org/repositories/home:/pzz/xUbuntu_20.04 InRelease: The following signatures were invalid: EXPKEYSIG 23E07629B9E3C9E4 home:pzz OBS Project <home:pzz@build.opensuse.org>
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.
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.
