Trixie is now using the new deb822 sources format. I have not built this ISO to check but Debian sources should be in /etc/apt/sources.list.d/debian.sources
If they are not, then its a Debian builder issue
config/archives/linuxcnc-uspace.list.binary (and the other additional sources files - Ethercat etc) should be in the new format
sudo apt modernize-sources takes your original sources files and outputs the correct files in the correct format (and backs up old files) You could use this to create correct files from an existing install
Trixie is now using the new deb822 sources format. I have not built this ISO to check but Debian sources should be in /etc/apt/sources.list.d/debian.sources
If they are not, then its a Debian builder issue
config/archives/linuxcnc-uspace.list.binary (and the other additional sources files - Ethercat etc) should be in the new format
sudo apt modernize-sources takes your original sources files and outputs the correct files in the correct format (and backs up old files) You could use this to create correct files from an existing install