HI there,
AE recognizes that the footage has fields, and de-interlaces it for display, if you render out the footage using fields, they’re back.
There’s no use in showing fields on a computer screen, because all you will see are distracting horizontal/vertical combs
It appears that Premiere is doing the same, but using a softer algorithm to de-interlace.
If you interpret your footage as having no fields, the sharpness in still images will be back, but you’ll run into trouble if you’re moving, scaling or rotating your video-layers.