When exporting an animation to gif, using the Export node, and then activating the option "Use Built-in gif encoder" the option "Animation - Loop" will be ignored and always be treated as "true".
If you have "Loop" deactivated and export with "Use Built-in gif encoder" the gif will still loop
If you now uncheck "Use Built-in gif encoder" and export again the gif won't loop (as expected)
When using the "Padding" node with the "Pad to size" Pad Mode then it will add pixels from the right and bottom size back to the top and left after padding. This should not happen. Everything is working fine though when using "Pad out". Reason is probably cause the source dimension is not dividable by the target dimension evenly?