I took a look and if I'm reading their post correctly then this isn't the same issue for us. As mentioned in the comments, we've had a number of updates to Pyramid Plunder over the years.
I can only look so far back but it's been the same drop rate since at least 2012 where it's simply a 1/1000 chance when rolling for a sceptre (which isn't the same code as OSRS).
In regards to where you get the sceptre from though...
- Grand Gold Chest - Runs the sceptre check if you don't disturb the scarabs
- Sarcophagus - Runs the sceptre check if you don't disturb a mummy
Both of these 'fail' actions do however have a higher chance in higher level rooms though, so I guess you could say that your chance of getting a sceptre does decrease the deeper you go.
EDIT - I spoke with Mod Kieren for clarity and their post is in relation to the fail chance on these actions, so we do have a similar issue here. I'll poke someone from QA to create a task to investigate and possibly address (if we feel it's needed for us).