Downscaling, or did you mean 1280x720 to FHD 1920x1080?
In past versions, there is a model selecting bug where the 4k version of the model was basically always selected. I have not tested with 3.1.0 to see if it’s still there, but it was there in the last version 3.0.12.
This post, sounds very similar to what’s going for you. If I’m not mistaken, it’s upscaling to 4k then downscaling to the output resolution using a common lanczos resizing filter.
