Cost Base Issue

I have noticed that none of the Cost basis calculations are correct.
for example this one:
63.899333 USDT
A$88.77 cost basis • 0.06389933 USDT / A$0.083 fee

For this to be correct 1 AUD would be worth 0.7198303 USDT
The last time this price was accurate was in November last year. the trade above was made today, where the value of 1 AUD is around 0.7688 USDT

That’s almost a 7% error.

Any help? or reason why this is like this? it basically makes the whole coin tracker worthless.