My run was rejected for starting under the stairs but the world record does the exact same, why is this allowed but mine isn't? https://www.speedrun.com/roblox_climb_2000_stairs_to_vip/run/mrel168y

Actually the timer started when he was right above the stairs, then he immediately went under it and did the glitch. The rules don't seen to have a place where the run officially starts. All it says is don't be underneath the stairs. The question is if does that mean anywhere else is free game?

I agree that the rules are very unclear but it's not really Quantum's fault. There's just no good way to put it. The way I would say it is that you have to touch the top of some part of the stairs. For WR I abused a mechanic where I could use parachute/umbrella to lower myself down to above the stairs closer to the teleportation pad under the stairs. If you look closely, as I'm moving down with umbrella, I let go of it and touch the railing, then I fall onto the pad. That part where I touched the railing is where the timer started. Long explanation, sorry if this was a bit redundant.