The "HD" versions streaming are just the original HDTV masters. The show was shot for old 1080i HDTVs, but the CG was still rendered in SD. The res switching can be annoying, especially in shots where there's a CG element with live action.
From my understanding, the old video toaster CG files are long lost, so if this is a true remaster they would've had to recreate the effects from scratch like they did with Star Trek TOS.