Unlike simple models (Non-XLs), using AziibPixelMix Pony XL makes the images somewhat "suspicious". For the purpose the model was trained for, I recommend using these settings:
Model: RDXL Pixel Art
Size: 3:5
Steps: 25+
Sam. Method: DDIM
CFG: 5.0 ~ 8.0
VAE: (I haven't tested it yet)
But feel free to test on other models and etc..