That is because the speeds are different on NBN to Cable...
Standard Speed for Telstra Cable is 30/1Mbps, most cases speed of up to 35/1.2Mbps were not unusual...
Telstra use NBN Co's Tier 2 NBN Speeds, which is a speed of 25/5 maximum... so based on that 23/5Mbps would be pretty close to target speed. (standard tier 1 speeds for NBN are only 12/1... which is what most providers offer)
So yes, that would be expected.
Standard Speed for Telstra Cable is 30/1Mbps, most cases speed of up to 35/1.2Mbps were not unusual...
Telstra use NBN Co's Tier 2 NBN Speeds, which is a speed of 25/5 maximum... so based on that 23/5Mbps would be pretty close to target speed. (standard tier 1 speeds for NBN are only 12/1... which is what most providers offer)
So yes, that would be expected.