went back to website instructions as remembered got similar error…

https://tonfotos.com/download.html

sudo apt-get update
Hit:1 http://repo.linuxliteos.com/linuxlite fluorite InRelease
Hit:2 https://dl.google.com/linux/chrome/deb stable InRelease
Get:3 http://security.ubuntu.com/ubuntu jammy-security InRelease [110 kB]
Hit:5 http://archive.canonical.com/ubuntu jammy InRelease
Get:4 https://tonfotos.com/distribution/tonfotos/5d299efaf8f84a3d58680a9891dc5701/linux/debian binary/ InRelease [17.2 kB]
Hit:6 http://us.archive.ubuntu.com/ubuntu jammy InRelease
Err:4 https://tonfotos.com/distribution/tonfotos/5d299efaf8f84a3d58680a9891dc5701/linux/debian binary/ InRelease
Clearsigned file isn’t valid, got ‘NOSPLIT’ (does the network require authentication?)
Get:7 http://us.archive.ubuntu.com/ubuntu jammy-updates InRelease [114 kB]
Get:8 http://us.archive.ubuntu.com/ubuntu jammy-backports InRelease [99.8 kB]
Get:9 http://us.archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages [631 kB]
Get:10 http://us.archive.ubuntu.com/ubuntu jammy-updates/main i386 Packages [330 kB]
Reading package lists… Done
E: Failed to fetch https://tonfotos.com/distribution/tonfotos/5d299efaf8f84a3d58680a9891dc5701/linux/debian/binary/InRelease Clearsigned file isn’t valid, got ‘NOSPLIT’ (does the network require authentication?)
E: The repository ‘https://tonfotos.com/distribution/tonfotos/5d299efaf8f84a3d58680a9891dc5701/linux/debian binary/ 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.

again could be me (linux newbie)

note, tonfotos is listed under software&updates>authentication> Trusted software providers

sorry I can’t upload image

Jacko note, tonfotos is listed under software&updates>authentication> Trusted software providers
sorry I can’t upload image

To upload image, just copy it from any image editor and paste it here.