After flop and turn bets get called, river is a good spot to bluff with A-high, but sizing should be around 60–70% pot; a small stab doesn’t apply enough pressure.
On K74r, we have a small range advantage but our actual hand is just A-high with no real equity. Solver prefers a lot of checking here, mixing in some small bets with hands like A6o. The 2BB c-bet is fine as a mix, but checking would also be very reasonable.
Turn is a blank; after flop c-bet gets called, we continue betting 4BB into 11.5BB. This sizing is on the small side for a deep-stacked pot, but it still pressures BB’s capped range and keeps our story consistent with a strong but not nutted hand.
River, pot is 19.5BB and we have 91BB behind. After flop and turn bets get called, BB’s range is fairly strong and condensed. With A-high and no real showdown value, this is a good candidate to bluff, but the sizing should be around 60–70% pot to really pressure one-pair and weaker hands; a small 2BB bet doesn’t apply enough pressure to fold out enough of BB’s range.