there are at least three different versions of the season 6 premiere I’m aware of:
-the original US broadcast version (which is on the US DVD minus the “previously on” segment), which runs about 89 minutes without commercials (86 minutes without the segment)
-the UK DVD version, which is a widescreen version of the same episode but it has the “previously on” segment restored, however the deer sacrifice scene has two shots cut from it
-the two part version which is on streaming services, it has various small cuts throughout and one scene is moved to another portion of the episode
Thanks - the broadcast masters header slate reports a “TRT” of 49:10 for S06E01 and 40:16 for S06E02, so 89:26 for the TV Movie. S06E02 is ‘short’ because it doesn’t include titles or a “previously on” segment (50 seconds and ~100 seconds respectively as streamed) - which, when added back in takes it to 42:46. I’m not sure about the accounting for the end credits/mutant enemy logo, but as streamed, 42:44 is the first frame of the end titles for S06E02 - so it feels like S06E02 is mostly complete.
However, I’ll run through both episodes side by side and note the cuts. One potentially controversial change is the end credits as broadcast have a split presentation with the bottom 40% showing titles and the top 60% showing a moon background “Buffy the Vampire Slayer” logo. This brings up the question of “as broadcast” vs “most complete”, but it’s not something that needs to be decided up-front.