Scaling down output size in Media Encoder from AE is buggy
When sending compositions to Media Encoder for rendering, scaling the output size down from the original size results in really bad, jaggy pixel scaling.
This only happens when exporting AE to Media Encoder, not when importing footage into Media Encoder or when exporting from Premiere to Media Encoder.
Antoine Autokroma commented
Did you try with AfterCodecs ? https://autokroma.com/AfterCodecs/ You can resize directly within After Effects render queue