The Illustrious paper states that year based tag modifiers were used during training,
Appending these tags at the end of generation does seem to impact generation quite a lot
Left to right
no year tag, newest, recent, modern, old, oldest
1girl, solo, summer dress, park, picnic, drinking water, eating pancakes, masterpiece
1girl, solo, portrait, depth of field, bokeh
1girl, solo, woodland nymph, dancing in a meadow, full body
1girl, solo, pressing face against window glass
Euler A, 20 Steps, CFG 7.0 - for all images
Negative prompt: worst quality, bad quality, low quality, watermark