The Blu-Ray edition of all 9 films are 4K ULTRA HD with HDR. They are higher bitrate than the Disney+ streams so therefore higher quality (and also NOT just copied from Disney+ with only subtitles added). The only difference is HDR10 compared to Disney+ Dolby Vision. It even says 4K UltraHD on the covers of both the single sets, trilogy sets and the complete collection box set, so do you even own the UHD Blu-Rays?
For example. The 2006 Bonus DVD theatrical versions cover said “widescreen” and “fullscreen” but they weren’t. And the 2020 Blu-ray is 4K HDR. The Sequel Trilogy and Prequel Trilogy is 4K UltraHD in the 2020 Blu-ray. There’s no doubt about it. But the Original Trilogy is HDR, not UltraHD.