The gif in the story was generated by adobe tools in the bad old days, circa 2005. I noticed the nerfing happened in the last 5 years when I looked closely at what Lightroom does.
In terms of wasted space, only 1/8th is actual xmp for that DJI exif chunk, the rest is padding for (13mb jpg:s in our case). 8k, so 1k actual xmp data of which a lot is structural. I've only tried with scripts, verifying with exiftool and a hex editor every now and then.
