I don't think these are connected with the Pre-Patch event. These are categorized as World Bosses in Dragonflight (see Dungeon Journal on PTR or on Beta) and the items have visuals of 10.0 tier sets. I believe the item level 280 is just an error and those will be bumped to like 350 ish area. Pre-patch even usually offers full set of gear not just 8 pieces out of 16. Pre-patch gear can be purchased in Orgrimmar and Stormwind if I recall correctly.
All the gear says lvl 70 requirement. I doubt its pre-launch catch up gear.
I hope there's catch-up gear like from Legion pre-patch. It was easy to aquire and there was a piece for every gear slot I believe. The good ol days.
The drake models shown above would make fantastic mounts!
Hopefully, the trinket from the last boss isn't tuned to be competitive with heroic/mythic raid ilvl trinkets. Having one shot a month on your BiS trinket is not a good feeling.
No mount drop which we gonna farm for the next decade ? Shame ...