I think the difference was that there was a shock factor, plus there were multiple lives on the line. Some of the more recent ones (Eden missing, Cash blacking out after arguing with Tim, Chloe killing her dad) have been about one (lesser) character the audience hasn’t been fully invested in, or it hasn’t been at the height of the drama.
The better cliffhangers of the past have involved a “who will die” type element with multiple characters at risk together where viewers are left on the edge of their seat to see if their favourite will come out unscathed, or changed forever - like the bus crash, hospital bomb, John Palmer’s fire, the Sutherland’s mine shaft collapse etc. When the show picks the favourite, it makes it harder for everyone to connect.
The show managed to do this jeopardy for Heather’s kidnapping of the heritage cast, and when Salt had the toxic gas… but is it too hard for the show to do these for the Aus finale, now that they are focusing on the UK finale?