According to online calculators:
A♥K♦ (57.91%) vs 7♣8♣ (41.71%)
A♥K♦ (59.42%) vs 8♣9♣ (40.19%)
A♥K♦ (58.59%) vs 9♣T♣ (41.00%)
Why is 8♣9♣ worse odds than the other 2?
I assume it has something to do with potentially dealing TJQ?
Yes it is steals
JQ steals and they need a T you have covered
When it need less cards to fill in the steal the steal is more common
9T is better than 89 as the T blocks the ace high straight
I am surprised 78 is better than 9T